Question 170715
so the portion of salt in the solution is .04(30)=1.2 oz----> this portion of salt does not change it simply becomes more diluted if pure water is added. The 1.2 ounces must be equal to 1.5% of what ever the new mix is....we know we already have 30 oz so whatever is added(water in this problem-which we will call x) has to be combined with the existing 30 oz as is stated in the problem.....so we end up with the new mix equaling 30+x

1.2=.015(30+x)
:
1.2=.45+.015x
:
.75=.015x
:
{{{highlight(x=50)}}}oz of pure water need to be added