Question

Sam Squeeze has 10 quarts of a drink that is 60% organge juice. how much pure orange juice must he add to get a drink that is 75% orange juice?

Answer 1

At the start there must be 6Q orange and 4Q water.

Let the total final volume =V
and the volume of orange added =v

so at the end

10Q+v=V..........1

and

(6Q+v)/V=0.75 or
6Q+v=0.75V.......2

solve the two equations (1 and 2) to find v