Question

You have $1.90 in dimes and nickels. You have a total of 29 dimes and nickels. How many dimes do you have?

Answer 1

Let d = number of dimes, n = number of nickels.

d + n = 29
10d + 5n = 190

Divide the second equation by 5: 2d + n = 38.
Subtract the first equation: (2d + n) − (d + n) = 38 − 29 ⇒ d = 9.

So you have 9 dimes.