RS Aggarwal Class 7 Math Seventh Chapter Linear Equation In One Variable Exercise 7C Solution

EXERCISE 7C

(3) If (2n+5)=3(3n-10), then n=?

(5) If 8(2x – 5) – 6(3x – 7) = 1, then x =?

Ans: (c)

(8) The sum of two consecutive whole numbers is 53. The smaller number is

Ans: (b)

(9) The sum of two consecutive even numbers is 86. The larger of the two is

Ans: (d)

Therefore, the larger number is (42 + 2) = 44

(10) The sum of two consecutive odd numbers is 36. The smaller one is

Ans: (b)

(11) On adding 9 to the twice of a whole number gives 31. The whole number is

Ans: (d)

(12) Thrice a number when increased by 6 gives 24. The number is

Ans: (a)

(14) Two complementary angles differ by 10^o. The larger angle is

Ans: (b)

(15) Two supplementary angles differ by 20^o. The smaller of the two measures

Ans: (b)

Therefore the smaller angle is (180^o – 100^o) = 80^o.

(16) The ages of A and B are in the ratio 5 : 3. After 6 years, their ages will be in the ratio 7 : 5. The present age of A is

Ans: (c)

Let the age of A is 5x and B is 3x.

After 6 years, A will be (5x + 6) and B will be (3x + 6).

The present age of A is (5 × 3) = 15 years.

(17) A number when multiplied by 5 is increased by 80. The number is

Ans: (b)

Let the number is x.

(18) The length of a rectangle is three times its width and its perimeter is 96 m. The length is

Ans: (c)

Let the width of the rectangle is x m and length is 3x m.

Therefore, the length is (3×12) = 36 m.