Andrew M. answered • 05/01/18

Mathematics - Algebra a Specialty / F.I.T. Grad - B.S. w/Honors

Look at the acid concentrations.

6 cl of 50% acid has 6(0.5) cl of acid

To this we add x cl of acid

To obtain (x+6)cl of 70% acid or 0.7(x+6)cl acid

x + 6(0.5) = (x+6)(0.7)

x + 3 = 0.7x + 4.2

0.3x + 3 = 4.2

0.3x = 1.2

x = 1.2/0.3

x = 4 cl of pure acid