9514 1404 393
Answer:
16 quarters; 9 dimes
Explanation:
If they were all dimes, Sasha would have $2.50. He has $2.40 more than that. Each quarter that replaces a dime adds $0.15 to the total, so there must have been $2.40/$0.15 = 16 dimes replaced by quarters.
Sasha has 16 quarters and 9 dimes in his pocket.
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If you like, you can write an equation for this. Let q stand for the number of quarters (higher value coin). Then the amount of cents in Sasha's pocket is ...
25q + 10(25-q) = 490
15q = 240
q = 240/15 = 16 . . . number of quarters
25-q = 9 . . . . . . . . . number of dimes
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Comment on the working
You may notice the solution to the equation we wrote follows the verbal solution presented first.