# Difference between revisions of "2009 AMC 8 Problems/Problem 21"

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− | First, note that <math>40A=75B=\text{sum of the numbers in the array}</math>. Solving for <math> \frac{A}{B}</math>, we get <math> \frac{ | + | First, note that <math>40A=75B=\text{sum of the numbers in the array}</math>. Solving for <math> \frac{A}{B}</math>, we get <math> \frac{A}{B}=\frac{75}{40} =\frac{15}{8}</math>. <math> \boxed{\text{D}}</math>. |

## Revision as of 08:32, 27 April 2012

## Problem

Andy and Bethany have a rectangular array of numbers with rows and columns. Andy adds the numbers in each row. The average of his sums is . Bethany adds the numbers in each column. The average of her sums is . What is the value of ?

## Solution

First, note that . Solving for , we get . .