d = 100-q
.10d + .25q = 21.40
Substitute 100-q for d in second equation and solve for q. Insert that value into the first equation and solve for d. Check by inserting both values into the second equation.
Stu has $21.40 in dimes and quarters for a totl of 100 coins. How many of each kind of coin does he have?
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2 answers