Question

I'm really bad with word problems, please help!

What quantity of a 50% acid solution must be mixed with a 35% solution to produce 300 mL of a 45% solution?

Answer 1

x = quantity of 50 % acid solution
y = quanity of 35% acid solution

x + y = 300 ml

0.5 * x + 0.35 * y = 0.45 * 300 ml
0.5 x + 0.35 y = 135 ml of acid
50 x + 35 y = 13500
10 x + 7 y = 2700

x + y = 300 => 10x + 10y = 3000
10x + 7 y = 2700

3y =3000 - 2700
3y = 300
y = 100

x + 100 = 300 => x = 200