I need help with this question.

Question

Gaby's piggy bank contains nickels and dimes worth $3.45. She has 56 coins in all. How many of each coin does Gaby have? Let x represent the number of nickels and let y represent the number of dimes.

Answer 1

5x+10y =345

x+y = 56

x=nickles = n

y = dimes = d

5n+ 10d = 345

n+d =56

5n+5d = 5(56) = 280

10d-5d = 345-280

5d = 65

d = 65/5 = 13 dimes

n = 56-13 =43 nickels

.05(43) + .10(13)

= 2.15 + 1.3

= $3.45