Question

I have $3.85 in my pocket in dimes and quarters only. I have three times as many dimes in my pocket as I do quarters. How many of each type of coin do I have?

Answer 1

You have `21` dimes and `7` quarters.

Explanation:

Let `x` be the number of quarters, and `3x` the number of dimes.

The amount of money you have can be written as `0.25x + 0.1*3x= 3.85`.

Now isolate `x` to find the number of quarters:
`0.25x + 0.1*3x = 3.85`
`0.25x + 0.3x = 3.85`
`0.55x = 3.85`
`x = 3.85/0.55 = 7 =` the number of quarters.

Then multiply by three to get the number of dimes: `7*3 = 21`

`7*$0.25 + 21*$0.1 = $3.85`