Answer :

MattD
a washer and a dryer cost 659$ combined. The washer costs 91$ less than the dryer, how much was the dryer?  
washer --> x
dryer --> y

x + y = 659$
y = x + 91$

x + x + 91$ = 659$

2x = 659$ - 91$

2x = 568$ |:2

x = 284$
y = x + 91$ = 284$ + 91$ = 375$

The dryer costs 375$ and washer costs 284$
W+D=659

W=D-91

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(D-91)+D=659

D-91+D=659

2D=750

D=750/2=375

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W+375=659

W=284

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So the dryer had cost $375 and the washer had cost $284.