Answer:
There are 33 quarters and 47 dimes
Step-by-step explanation:
Let the number of quarters be q.
Let the number of dimes be d.
There are 80 coins in total. Therefore:
q + d = 80 ________(1)
The total value of coins is $13.
The value of a quarter is $0.25 and the value of a dime is $0.10. This means that:
0.25q + 0.10d = 13 _____(2)
We have a system of equations:
q + d = 80 ________(1)
0.25q + 0.10d = 13 ____(2)
From (1):
q = 80 - d
Put this in (2):
0.25(80 - d) + 0.10d = 13
20 - 0.25d + 0.10d = 13
Collecting like terms:
-0.15d = 13 - 20
-0.15d = -7
d = -7 / -0.15
d ≅ 47
Therefore:
q = 80 - 47 = 33
There are 33 quarters and 47 dimes.
