You can
put this solution on YOUR website!Let's say we have n nickels and d dimes. That means that:

, because that is the number of coins we have altogether.
A nickel is worth 5 cents, so the value of all of the nickels is 5n cents. Likewise, the value of all of the dimes is 10d.
Just because I don't like mucking about with decimal coefficients, let's change the total amount of money from $22.40 to 2240 cents.
Now we can say that
We can re-state the first equation by solving it for either of the variables. Let's solve it for d:
Now take this expression for d and substitute it into the second equation:
So there were 160 nickels.
Check the answer.
If there were 160 nickels, then there were 144 dimes (304 - 160). 144 dimes is $14.40, 160 nickels is $8.00. $14.40 + $8.00 = $22.40. Answer checks.