Question 950336
Let's call one brand a and the other b.

a + b = 310. Therefore, a = 310 - b. And,
.08a + .13b = .09(310) Let's substitute in this equation with what we learned on the first equation (we learned that a= 310-b):

.08(310-b) + .13b = .09(310) Let's simplify, multiply:
24.8 - .08b + .13b = 27.9 Subtract 24.8, both sides:
- .08b + .13b = 3.1 Subtract on the left:
.05b = 3.1 Divide both sides by .05:
b = 62 OK, we need 62ml of .13 and 300 - 62 = 238ml of the .08 solution.