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QWhat number was the boy supposed to multiply by 12, but instead multiplied by 21 and got an answer 63 more than the correct answer?

ID: #4447 Numbers 232 views
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#4447Q ID
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  • A 7 ✔ ✖
  • B 9 ✔ ✖
  • C 12 ✔ ✖
  • D 15 ✔ ✖
Correct Answer: Option A

Explanation

Let's say the number that the boy was supposed to multiply by 12 is x. We know that the boy multiplied this number by 21 instead, and got an answer that was 63 more than the correct answer. Therefore, we can write the equation:

12x + 63 = 21x
Subtracting 12x from both sides of the equation, we get:

63 = 9x
Dividing both sides of the equation by 9, we get:

7 = x
Therefore, the number that the boy was supposed to multiply by 12 is 7.

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