Question

Bess has $2.80 in quarters and dimes. The number of dimes is 7 less than the number of quarters. Find the number of quarters and dimes

Answer 1

Answer:

3 dimes and 10 quarters

Step-by-step explanation:

If you add 7 dimes, then the number of dimes and quarters is the same, and the total increases to $3.50. A dime and a quarter have a value together of $0.35. Since there are equal numbers, the value $3.50 must be made up of some quantity of groups with a value of $0.35. That number of groups must be ...

... $3.50/$0.35 = 10

Thus, there are 10 quarters and 10-7 = 3 dimes.

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Using an equation

Let q represent the number of quarters. Then the amount Bess has is ...

... 0.10(q -7) +0.25q = 2.80

... 0.35q - 0.70 = 2.80

... 0.35q = 3.50 . . . . . add 0.70 . . . . . . . this should look familiar

... q = 3.50/0.35 = 10