We need to multiply how much each coin is worth by the number of each type of coin we have.
If we have x quarters then we multiply x by .25 and we have y dime then we multiply y by .10 and we have z nickels then we multiply z by .05. To find out how much money we have, we add it all up
Our equations becomes
.25*x +.10*y +.05*z
We have x=3 or 3 quarters, y = 5 or 5 dimes and z=2 or 2 nickels