Brine is a solution of salt and water. If a tub contains 50 gallons of a 5% solution of brine, how much water must evaporate to change it to an 8% solution?

Let x = amt of water evaporated

.05 (50) =.08 (50-x)

2.5 = 4 -.08x

.08x = 4 - 2.5

.08x = 1.5

x =

x = 18.75 lb of water evaporated

Check; amt of salt remains the same, only the percentage is different, right?

.05 (50) =.08 (50-18.75)

.05 (50) =.08 (31.25)

2.5 = 2.5