<span>Lets n be the number of nickels Sue has.
Then the number of dimes is equal to (16-n).
So, Sue has 5*n cents in nickels and 10*(16-n) cents in dimes.
Since the total amount Sue has is $1.15, or 115 cents, it gives you an equation
5n + 10*(16-n) = 115.
Simplify this equation:
5n +160-10n = 115 (after opening parentheses)
-5n = 115-160 (after collecting like terms at the left side and moving 160 to the right side with the opposite sign)
-5n = -45 (after collecting like terms at the right side)
n = 9 (after dividing both sides by -5).
So, the number of nickels is equal to 9.
The number of dimes is equal to 16 minus the number of nickels, that is
16-n = 16-9 = 7.
Check.
The total number of coins is equal to 9 + 7 = 16.
The total amount is equal to 9*5 + 7*10 = 45 + 70 = 115.
The solution is correct.
