Question

A solution contains6​% salt. How much water should be added to 70 ounces of this solution to make a 4.2​% ​solution?

Answer 1

.07(70) = .049(x+70)
4.9 = .049x + 3.43
4.9 - 3.43 = .049x
1.47 = .049x
x = 1.47/.049
x = 30 oz of water added to the 70 oz

Answer 2

0.06(70)=4.2 oz salt
4.2=4.2% in how much total
4.2=4.2% of total
4.2=0.042 times total
divide both sides by 0.042
100 =total

70+what=100
what=30

30 oz of water must be added