A collection of 22 dimes and quarters has a total value of $4.00. Write a system of equations that defines this situation and solve using any method.

Since dimes + quarters = 22
And dimes are 0.10 cents as quarters = 0.25 cents
Let’s make d = dime, q = quarter
d + q = 22
0.10d + 0.25q = 4.00
Let’s use substitution
d + q = 22, get d or q by itself
d = 22 - q (plug into second equation)
0.10(22-q) + 0.25q = 4
2.2 - 0.10q + 0.25q = 4
2.2 + 0.15q = 4
0.15q = 1.8, q = 12
Since there are 12 quarters you know there are 10 dimes (22 in total)

Solution: 10 dimes, 12 quarters