SOLUTION: How can I make $5.11 out of 31 coins? I can only use pennies and quarters

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Question 157929: How can I make $5.11 out of 31 coins? I can only use pennies and quarters
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Let's call the pennies P and quarter Q.
Each penny is worth $0.01 and each quarter $0.25.
Total number of coins is 31.
1.P+Q=31
Total value of coins is $5.11.
2.$0.01*P+$0.25*Q=$5.11
Let's multiply both sides of eq. 2 by 100 to get rid of decimals.
2.P%2B25Q=511
From eq. 2,
2.P%2B25Q=511
P=511-25Q
Substitute this expression into eq. 1 and solve for Q.
1.P%2BQ=31
%28511-25Q%29%2BQ=31
-24Q=31-511
-24Q=-480
highlight%28Q%29=20
from above
P=511-25Q
P=511-25%2820%29
P=511-500
highlight%28P%29=11
11 pennies abd 20 quarters.