a + b = 30 ----> a = 30 - b
10a + 5b = 235
Substitute!
10(30 - b) + 5b = 235
300 - 10b + 5b = 235
5b = 65
b = 13
Adrianna M.
asked 03/05/19A jar of 30 bills contains only $5's and $10's. If the total amount is $235, how many $5 dollar bills are there in the jar?
a + b = 30 ----> a = 30 - b
10a + 5b = 235
Substitute!
10(30 - b) + 5b = 235
300 - 10b + 5b = 235
5b = 65
b = 13
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