Let n = number of nickels. Then the number of dimes is 22-n. The "value" equation is 5n + 10*(22-n) = 150. Simplify and solve for n: 5n + 220 - 10n = 150, -5n = 150 - 220, -5n = -70, n == 14. The number of nickels is 14. The number of dimes is 22-14 = 8. Check. 5*14 + 10*8 = 70 + 80 = 150.