Question 163980This question is from textbook Algebra and Trigonometry
: Kerry asked a bank teller to cash a $390 check using $20 and $50 dollar bills. If the teller gave her a total of 15 bills, how many of each type of bill did she recieve?
I don't even know where to start on this problem, please help me.
This question is from textbook Algebra and Trigonometry
Answer by Alan3354(69443)   (Show Source):
You can put this solution on YOUR website! Kerry asked a bank teller to cash a $390 check using $20 and $50 dollar bills. If the teller gave her a total of 15 bills, how many of each type of bill did she recieve?
I don't even know where to start on this problem, please help me.
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Start by writing what is known.
Call the $20 bills T and the $50 bills F.
He got 15 bills, so T+F = 15. See that?
Then, 20T + 50F = 390. See that? Each $20 bill, or T is 20, etc.
Now there are 2 eqns in 2 unknowns.
T+F = 15
20T + 50F = 390
From the 1st eqn, T = 15-F
Substitute that into the 2nd eqn.
20*(15-F)+ 50F = 390
300 - 20F + 50F = 390
30F = 90
F = 3 (he got 3 $50 bills)
T has to be the other 12, so
T = 12
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As a check:
20*12 + 50*3 does equal 390
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