How much 80 percent solution must be added to 30 percent to get 200 liter of 62 percent solution?

We let X=For 80 percent, then, the rest is 200-X which represents for 30 percent. We write the equation as follows:

X(0.8)+(200-X)0.3 = (200)(0.62)

We solve the equation and we get X=128 liter at 80 percent and 72 liter at 30 percent.