Lesson eLearning

If a number between 10 and 20 is increased by 5, the result is 18. What was the original number?

medium 2 marks Class 1 · Mathematics · Numbers from Ten to Twenty
Answer
13

The correct answer is 13 — So the original number is .

Step-by-step solution

  1. Let the original number be .
  2. The increased number is .
  3. Subtract 5 from both sides: .
  4. Compute: .
  5. So the original number is .
Common mistake: Adding instead of subtracting

Concept tested: Subtraction to find an unknown number

Published · How this solution was prepared and checked

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