Question 4748
Let N = # of nickels.  A nickel = $0.05
Let D = # of dimes.     A dime = $0.10

The # of nickels plus the # of dimes = 175 (The total number of coins)
N($0.05) + D($0.10) = $11.90 (The total value of the coins)

The equations you need are:
  N + D = 175
N($0.05) + D($0.10) = $11.90

Solve this system of equations for N and D and you will have solved the problem.

I got: N = 112 and D = 63