Bunuel wrote:

Some part of a 50% solution of acid was replaced with an equal amount of 30% solution of acid. If, as a result, 40% solution of acid was obtained, what part of the original solution was replaced?

A. \(\frac{1}{5}\)

B. \(\frac{1}{4}\)

C. \(\frac{1}{2}\)

D. \(\frac{3}{4}\)

E. \(\frac{4}{5}\)

Hi,

Can I got the answer right but I hope my approach is correct in tackling this question. Let x equal to the original solution, now if we remove 50% from the original we get:

100%x - 50%x = 50%x remaining solution

from the remaining solution, 30% was added. Therefore we get 50%x+30%x = 80%x now we know the remaining is 40% solution. So we can create an equation of 80%x=40% and now if we isolate x we get 1/2 -> Answer choice C