Alegebra Story Problem

[twins12]

How much water must be evaporated from 200 lb of a 10% salt solution to yield a solution that is 18% salt?
Amount=___________ lb

 

[galactus]

The amount of salt remians the same. Initially, there is 200 lbs of solution with 20 lbs of that being salt.

So, to get the 18%, $\displaystyle 200-\frac{20}{0.18}$ has to be evaporated.

But, to set it up algebraically, let x=amount to be evaporated:

.18(200-x)=.10(200) and solve for x.