SOLUTION: Ajax has $3.70 in dimes and quarters. If the dimes were quarters, and the quarters were dimes, the money would have been $4.00. How many coins does ajax have?

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Question 740793: Ajax has $3.70 in dimes and quarters. If the dimes were quarters, and the quarters were dimes, the money would have been $4.00. How many coins does ajax have?
Answer by checkley79(3341) (Show Source):
You can put this solution on YOUR website!
.25Q+.10D=3.70 MULTIPLY BY -2.5 & ADD.
[MULTIPLYING THE .10D BY -2.5=-.25D SO I COULD ELIMINATE THE 2.5D IN THE SECOND EQUATION THUS SOLVING THE 2 EQUATIONS FOR THE UNKNOWN VALUE Q]
[ I COULD HAVE DIVIDED THE .25Q TERM BY -2.5=-.10 & ELIMINATE THE Q TERM INSTEAD]
.10Q+.25D=4.00
-.625Q-.25D=-9.25
--------------------------
-.525Q=-5.25
Q=-.525/5.25
Q=10 NUMBER OF QUARTERS.
.25*10+.10D=3.70
2.50+.10D=3.70
.10D=3.70-2.50
.10D=1.20
D=1.20/.10
D=12 NUMBER OF DIMES.
PROOF:
.10*10+.25*12=4.00
1.00+3.00=4.00
4.00=4.00