a piggy bank contains 85 coins, all dimes and nickles, worth $6.80. How many of each type of coin does the piggy bank contain.

Question

 This is a word problem that I am confused how to do.

Answer 1

Since we have two unknowns, nickels (n) and dimes (d), we will need two equations.

 

n + d = 85

.05n + .10d = 6.80

 

n = 85 - d

 

.05(85 - d) + .10d = 6.80

4.25 - .05d + .10d = 6.80

4.25 + .05d = 6.80

.05d = 2.55

d = 51

n = 85 - d = 85 - 51 = 34

 

So there are 34 nickels and 51 dimes.