Question 844890
Just with that information, we could expect the percents to be as w/v.


Let v = how much volume of the pure acid to add


{{{(50*4+100v)/(v+4)=80}}}
Solve for v


Study this lesson to understand better:
http://www.algebra.com/tutors/Two-Part-Mixture-with-one-material-quantity-unknown.lesson?content_action=show_dev