Question 571189
Gertie has $9.20. All of her coins are dimes and quarters. The number of quarters is 1 less than the number of dimes. How many of each coin does Gertie have? 
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Let d = the number of dimes
Then the number of quarters = d-1
The total amount is 920 = 10d + 25(d-1)
Solve for d:
920 = 10d + 25d - 25
35d = 945
d = 27
So she has 27 dimes, 26 quarters