Question 1066294
$4 total in dimes and quarters, and there is a total of 25 coins. How many dimes and quarters?
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Another method, but probably not enough to get a PHD in math:
25 dimes = $2.50
Each dime replaced by a quarter adds 15 cents.
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400 - 250 = 150 cents
150/15 = 10 replacements.
--> 10 quarters & 15 dimes