There are x nickels and (x+7) dimes. The total money equation is 5x + 10*(x+7) = 415 cents. Simplify this equation and find x 5x + 10x + 70 = 415 15x = 415 - 70 15x = 345 x = 345/15 = 23. ANSWER. 23 nickels and 30 dimes. CHECK. 23*5 + 30*10 = 115 + 300 = 415 cents. ! correct !