Class 7 Variables on Both Sides — practice questions with answers

Simple Equations · 5 sample questions from the school syllabus. Try each one, then open the answer and the worked solution.

1. Solve for x: 5x = 3x + 8

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Answer: A) 4

5x - 3x = 8, so 2x = 8, giving x = 4.

2. Solve for x: 8x + 3 = 5x + 3

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Answer: A) 0

8x - 5x = 3 - 3, so 3x = 0, giving x = 0.

3. Solve for x: 9 - x = 2x - 3

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Answer: A) 4

9 + 3 = 2x + x, so 12 = 3x, giving x = 4.

4. Solve for x:

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

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Answer: A) 12

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

, so

\frac{x}{3} = 4

, giving x = 12.

5. Two brothers, Dev and Rohan, save money weekly. Dev's savings after x weeks is Rs (120x + 200) and Rohan's is Rs (150x + 50).
Form an equation for when their savings are equal and find x (in weeks). Then state Dev's savings at that time (in Rs).

Ax = 5, Rs 800
Bx = 5, Rs 750
Cx = 4, Rs 680
Dx = 6, Rs 920

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Answer: A) x = 5, Rs 800

120x + 200 = 150x + 50, so 200 - 50 = 150x - 120x, 150 = 30x, x = 5. Dev's savings = 120(5) + 200 = 600 + 200 = Rs 800.

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