word problem

Question

if there is 118 ozs.of 50%saline solution.how may ounces of a 30% solution need to be added to original solution in order to have a solution with 100.4 ounces of salt in the mixture?

Answer 1

In the 118oz solution half the weight is salt, so we have 59oz of salt.

If we add x ounces of a 30% solution the amount of salt is 0.3x ounces.

So 59+0.3x=100.4; 0.3x=41.4 so x=41.4/0.3=414/3=138oz.