Keana’s piggy bank contains $4.30 in nickels and dimes only. If she has 59 coins in her bank, then what is the sum of the digits in the number of nickels in Keana’s bank? Write a system of equations for this situation and find its solution.
n + d = 59 {she has 59 coins total} 5n + 10d = 430 {value of coin times number of coins equals total value}
-5n - 5d = -295 {multiplied top equation by -5} 5n + 10d = 430 {bottom equation stays the same} --------------- 5d = 135 {added the two equations} d = 27 {divided each side by 5}
n + d = 59 {first original equation} n + 27 = 59 {substituted 27, in for d, into first original equation} n = 32 {subtracted 27 from each side}
27 dimes 32 nickels
To answer the question, "what is the sum of the digits in the number of nickels?", add 3 + 2 = 5
