Reverse Plugging In: Basic Technique

The product of Ron's age and half of George's age is 42. If Ron is five years older than George is, then how old is Ron?

Incorrect. [[snippet]]

Incorrect. [[snippet]]

Incorrect. [[snippet]]

Incorrect. [[snippet]] Seven is George's age (five years younger than Ron). You may have reached this answer choice by incorrectly interpreting the results of an solving an set of simultaneous equations built on the information of the question. This is exactly the sort of careless error that __Reverse PIug In__ helps you avoid by plugging the answers directly for the variable requested by the question—how old Ron is.

Correct. [[snippet]] __Plugging In__ E works: If Ron is 12, George is seven and the product of Ron's age and half of George's age is $$12\times\frac{7}{2}=42$$.

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