algebra word problems
posted by mike .
you have 95 coins that total $10.75. the coins consist of only quarters and nickels. how many of each coin do you have?

.25q+.05n=10.75 (1)
q+n=95 (2)
Multiply (2) by .25 to cancel the q's
.25q+.05n=10.75 (1)
.25q.25n=23.75 (3)
.2n=13
Divide both sides by .2
n=65
From (2), q+n=95, q+65=95, q=30
When plugged back into equation 1, it checks. It works in both equations, so this is your solution. 
You have a total of $175 in $5 and $20 bills. The number of $5 bills you have is 3 more than 4 times the number of $20 bills. How many of each type of bill do you have?