Practice30Create account

Solving , Kabir wrote and answered . What is his error and the correct value of ?

Class 7Simple EquationsSimple Equations
  • AHe should have written , giving
  • BNothing is wrong; is correct
  • CHe should have written , giving
  • DHe should have subtracted 5 as well, giving

Step-by-Step Solution

A term that crosses the '=' sign flips its sign, so the +12 on the left becomes −12 on the right: → . Check: ✓. Kabir kept the plus sign — the commonest transposition slip of all. Reversing the whole subtraction (12 − 47) flips one sign too many.
Answer: C) He should have written , giving

Key idea: Solving by the balance method

Example: solve .

Step 1: undo the +2 by subtracting 2 from BOTH sides.


Step 2: undo the ×3 by dividing BOTH sides by 3.
Verify**: substitute back. ✓. Always check by substitution — it catches sign errors instantly.

Master this chapter in 30 minutes a day.

Don't just memorise the answer — build a daily practice habit.

Practice 5 Similar Questions Free →

All Simple Equations practice questions

More Class 7 Simple Equations practice

To solve 8x = 96, Sneha wrote 8x ÷ 8 = 96 and gave the answer x = 96. What went wrong?An auto-rickshaw in Nagpur charges a fixed ₹40 plus ₹20 for every kilometre travelled.…In a quiz every correct answer scores 5 marks and every wrong answer loses 2 marks. Anil…The sum of three consecutive odd numbers is 81. What is the largest of the three?At a Diwali party a packet of 76 sweets is shared equally among 8 children, and 4 sweets…