Question 426992
A bank teller has 54 $5 and $20 bills in her cash drawer. The value of the bills of $780. How many $5 bills are there? 
Quantity Eq: f + t = 54 bills
Value Eq:   5f+20t = 780 dollars
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Divide thru the Value Eq by 5 
f+t = 54
f+4t=156
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Subtract and solve for "t":
3t =102
t = 34 (# of $20 bills)
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Solve for "f":
f+t = 54
f+34 = 54
f = 20 (# of $5 bills)
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Cheers,
Stan H.
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