Part of the proceeds from a garage sale was $400 worth of $10 and $20 bills. If there were 7 more $10 bills than $20 bills, how many of each bills were there?

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Answer 1 · 2016-02-03T22:49:31

18 $10 bills and 11 $20 bills

Lets say there are #x# 10 dollar bills and #y# 20 dollar bills

from the information given

1) #10x + 20y = 400#

there are 7 more 10 dollar bills than 20 dollar bills therefore
2) #x = y+7#

substituting equation 2 into equation 1
#10y +70 +20y = 400#

rearranging
#y=(400-70)/30 = 11#

putting the #11# back into equation 2
#x = 11+7 = 18#

Therefore there are 18 $10 bills and 11 $20 bills