How much pure acid should be added to 6L of 30 acid to incre

How much pure acid should be added to 6L of 30% acid to increase the concentration to 50% acid?

Let x L of pure acid must be added

Then;

0.30*6 + 1*x = 0.50(6+x)

Multiply by 100 throughout

6(30) + 100 x = 50(6+x)

=> 180+100x=300+50x

=> 50x = 120

=> x = 120/50 = 12/5 = 2.4L

So 2.4L of pure acid must be added