Question 300691
let olga have x nickels  and y dimes

5x=y

or

5x-y =0

5x+10y=330 cents

x+2y= 66

2(5x-y)+x+2y=66

10x-2y +x +2y= 66

11x=66

x= 6 the number of nickels

5*6 = 30 is the number of dimes.