Mathematics

Linear Equations in One Variable

Question:

An employee works in a company on a contract of 30 days on the condition that he will receive Rs 120 for each day he works and he will be fined Rs 10 for each day he is absent. If he receives Rs 2300 in all, for how many days did he remain absent?

Answer:

ncert-exemplar-problems-class-8-mathematics-linear-equations-in-one-variable-34

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Linear Equations in One Variable

Q 1.

If –frac { 4 }{ 3 } y = –frac { 3 }{ 4 } then y is equal to
(a)-{ left[ frac { 3 }{ 4 } 
ight] }^{ 2 } (b)-{ left[ frac { 4 }{ 3 } 
ight] }^{ 2 }
(c){ left[ frac { 3 }{ 4 } 
ight] }^{ 2 } (d){ left[ frac { 4 }{ 3 } 
ight] }^{ 2 }

Q 3.

The age of A is five years more than that of B. 5 years ago, the ratio of their ages was 3 :2. Find their present ages.

Q 4.

Which of the following is a linear expression?
(a) { x }^{ 2 } +1 (b) y + { y }^{ 2 }
(c) 4 (d) 1 + z

Q 5.

If the sum of two consecutive numbers is 93 and one of them is x, then the other number is 93 – x.

Q 7.

8x-7-3x=6x-2x-3

Q 8.

When a number is divided by 8, the result is -3. The number is——–.

Q 9.

If  frac { 2 }{ 5 } x-2=5- frac { 3 }{ 5 } x,then x=——-.

Q 10.

The number of boys and girls in a class are in the ratio 5 : 4. If the number of boys is 9 more than the number of girls, then number of boys is 9.

Q 11.

Rs 13500 are to be distributed among Salma, Kiran and Jenifer in such a way that Salma gets Rs 1000 more than Kiran and Jenifer gets Rs 500 more than Kiran. Find the money received by Jenifer.

Q 12.

Sum of the digits of a two-digit number is 11. The given number is less than the number obtained by interchanging the digits by 9. Find the number.

Q 13.

When 9 is subtracted from the product of p and 4, the result is 11. The value of p is—-.

Q 14.

If  frac { 2 }{ 5 } x-2=5- frac { 3 }{ 5 } x,then x=——-.

Q 15.

Sum of the ages of Anju and her mother is 65 years. If Anju’s present age is y years, then her mother’s age before 5 years is (60 – y) years.

Q 16.

ncert-exemplar-problems-class-8-mathematics-linear-equations-in-one-variable-1

Q 17.

If 6x = 18, then 18x = 54.

Q 18.

 frac { y-(4-3y) }{ 2y-(3y+4y) } =frac { 1 }{ 5 }

Q 19.

0.4(3x-1)=0.5x +1

Q 20.

5(x-1)-2(x+8)=0

Q 21.

frac { 3t-2 }{ 3 } +frac { 2t+3 }{ 2 } =t+frac { 7 }{ 6 }

Q 22.

The value of x, for which the expressions 3x – 4 and 2x + 1 become equal, is
(a) -3 (b) 0
(c) 5 x (d) 1

Q 23.

15 The sum of three consecutive multiples of 7 is 357. Find the smallest multiple.(a) 112 (b) 126 (c) 119 (d) 116

Q 24.

Any value of the variable, which makes both sides of an equation equal, is known as a———–of the equation.

Q 25.

A term of an equation can be transposed to the other side by changing its—-.

Q 26.

frac { 5x }{ 2x-1 } =2

Q 27.

frac { 0.2x+5 }{ 3.5x-3 } =frac { 2 }{ 5 }

Q 28.

4t-3-(3t+1)=5t-4

Q 29.

1-(x-2)-[(x-3)-(x-1)]=0

Q 30.

 frac { 5x+1 }{ 2x } =-frac { 1 }{ 3 }

Q 31.

The sum of three consecutive odd natural numbers is 69. Find the prime number out of these numbers.

Q 32.

The perimeter of a rectangle is 240 cm. If its length is increased by 10% and its breadth is decreased by 20%, then we get the same perimeter. Find the length and breadth of the rectangle.

Q 33.

The solution of the equation 3x – 4 = 1 – 2x is————- .

Q 34.

The denominator of a rational number is greater than the numerator by 10. If the numerator is increased by 1 and the denominator is decreased by 1, then expression for new denominator is——.

Q 35.

The sum of two consecutive multiples of 10 is 210. The smaller multiple is——-.

Q 36.

ncert-exemplar-problems-class-8-mathematics-linear-equations-in-one-variable-3

Q 37.

If x is an even number, then the next even number is 2(x +1).

Q 38.

Two numbers differ by 40. When each number is increased by 8, the bigger becomes thrice the lesser number. If one number is x, then the other number is (40 – x).

Q 39.

 frac { 2y-3 }{ 4 } -frac { 3y-5 }{ 2 } =y+frac { 3 }{ 4 }

Q 40.

The sum of three consecutive even natural numbers is 48. Find the greatest of these numbers.

Q 41.

The sum of four consecutive integers is 266. What are the integers?

Q 42.

A steamer goes downstream and covers the distance between two ports in 5 hours, while it covers the same distance upstream in 6 hours. If the speed of the stream is 1 km/h, then find the speed of the steamer in still water.

Q 43.

For what value of x is the perimeter of shape 77 cm?

ncert-exemplar-problems-class-8-mathematics-linear-equations-in-one-variable-40

Q 44.

If a and b are positive integers, then the solution of the equation ax = b has to be always
(a) positive (b) negative (c) one (d) zero

Q 45.

In questions 16 to 32, fill in the blanks to make each statement true.
Question. 16 In a linear equation, the——— power of the variable appearing in the equation is one.

Q 46.

 frac { x }{ 5 } + 30 = 18 has the solution as——–.

Q 47.

After 18 years, Swarnim will be 4 times as old as he is now. His present age is——–.

Q 48.

Convert the statement ‘adding 15 to 4 times x is 39’ into an equation.

Q 49.

3 years ago, the age of boy was y years. His age 2 years ago was (y — 2) years.

Q 50.

Shikha’s present age is p years. Reemu’s present age is 4 times the present age of Shikha. After 5 years, Reemu’s age will be 15p years.