Math
posted by Gabe .
i need to know exactly the formula of how to do these types of problems because i have spend seriously over an hour trying to do this one problem. HELP!
A dealer mixes candy worth 90 cents per pound with candy worth 65 cents per pound in order to obtain 40 pounds of candy to be sold at 75 cents per pound. how many pounds of the 90 cent candy should be used?

There is no "formula" to solve these kind of problems, you basically have to translate the English into a mathematical statement.
let the number of pounds of the 90 cent candy be x
then the amount of 65 cent candy is 40x pounds.
so....
90x + 65(40x) = 75(40)
Now just solve that equation.