Question 736003
 Paul E. Bank has $2.25 in quarters and dimes. He has 15 coins.
 Find the number of quarters and dimes he has.
:
Let d = no. of dimes
Let q = no. of quarters
:
Write an equation for each statement.
"
" Paul E. Bank has $2.25 in quarters and dimes."
.10d + .25q = 2.25
:
" He has 15 coins." 
d + q = 15
We can use substitution here, change the equation to:
d = (15-q)
:
Replace d with (15-q) in the second equation
.10(15-q) + .25q = 2.25
1.5 - .10q + .25q = 2.25
-.10q + .25q = 2.25 - 1.5
.15q = .75
q = .75/.15
q = 5 quarters
I'll let you find the number of dimes, check solutions in the 1st equation