2. A collection of dimes and quarters has a total value of five dollars and contains 29 coins. How many dimes are there in the collection?(Hint... find two equations)

Answer 1

let d be the number of dimes

let q be the number of quarters

then we can set up the two equations:

d + q = 29

.10d + .25q = 5.00

solve the first equation for q and substitute into the second equation

d + q = 29

q = 29 - d

.10d + .25q = 5.00

.10d + .25(29 - d) = 5.00

.10d + 7.25 - .25d = 5.00

7.25 - .15d = 5.00

-.15d = -2.25

d = 15