# Question #f7dd5

Oct 2, 2017

#### Explanation:

X is the amount from acid solution 20% and (400-X) is the amount from acid solution 60%. Final volume will be 400 mL of 40% acid solution.

$X \times 0.20 + \left(400 - X\right) \times 0.60 = 400 \times 0.40$

$0.2 X + 240 - 0.6 X = 160$

$240 - 160 = 0.4 X$

$80 = 0.4 X$

$200 m L = X$

Take 200 mL from 20% acid solution and 200 mL from 60% acid solution, mix well and you will get 40% acid solution (volume 400 mL).