Question

A student solved this problem by working backward.

A number is multiplied by 7. Then 29 is added to the product. This sum is then divided by 2. The answer is 46. What was the original number?

Student's solution - The answer was 46. If this was the result of dividing by 2, the number at this point was 92. If this was the result of adding 29, the number at this point was 63. If this was the result of multiplying by 7, the original number was 9.

Solve this problem using a similar strategy.

A number is multiplied by 10. Then 32 is added to the product. This sum is then divided by 4. The answer is 28.

What was the original number?

Answer 1

28 is a result of dividing by 4, so you multiply 4 * 28 to get 112. Then, you subtract 32 because it was added to get that number. 112 - 32 is 80. Finally, you know the first number was multiplied by 10 to get 80, so you divide by 10 and get 8 as your answer.