My algebra teacher gave me this question.
Mr.Lynch has 21 coins in nickles and dimes. Their total value is 1.65. How many of each coin does he have?
Please help me, it's due tomorrow!

You need to set up a system of equations and solve it.
A nickel is worth $0.05, a dime $0.10.
If you have X nickels and Y dimes, then
X*$0.05+Y*$0.10=$1.65
and
X+Y=21