



 
The simple answer is "not much." Good Hunting!
Jordan, Suppose you were asked to calculate $9 \times 7 + 9 \times 3.$ You could find $9 \times 7$ and $9 \times 3$ and add the results but you could also notice that you have seven nines and then three more nines so that you have in total ten nines which is ninety. That is $9 \times 7 + 9 \times 3 = 9 \times (7 + 3) = 9 \times 10 = 90.$ This process of extracting a common factor can be applied to your problem also, $15 \times x + 15 \times y = 15 \times (x + y).$ Penny  


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