SOLUTION: Ann has $3.20 in 10 cents coins and 25 cents coins. If she has twenty coins altogether, find how many of each type of coin she has.

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Question 1176731: Ann has $3.20 in 10 cents coins and 25 cents coins. If she has twenty coins
altogether, find how many of each type of coin she has.
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

let 10 cents coins be d and 25 cents coins q
if she has twenty coins altogether, we have
d%2Bq=20
d=20-q....eq.1
1d=$0.10
1q=$0.25
if Ann has $3.20, then
0.10d%2B0.25q=3.20.....substitute d from eq.1
0.10%2820-q%29%2B0.25q=3.20
2-0.10q%2B0.25q=3.20
0.15q=3.20-2
0.15q=1.20...both sides multiply by 100 to get rid of decimals
15q=120
q=120%2F15
q=8
go to eq.1
d=20-q....eq.1, substitute q
d=20-8
d=12
so Ann has 12 of 10 cents coins and 8 of 25 cents coins