Question

How much alfalfa does Helmut need to add to 30L of ostrich pellets to make a feed mix that is 40% alfalfa by volume?

I have the formula down, the answer sheet says the answer is 20L.

Answer 1

a = 20 . . . . liters

Explanation:

To solve this, multiply the equation by 30+a:

a = 0.4(30 +a)

a = 12 + 0.4a . . . . . eliminate parentheses

0.6a = 12 . . . . . . . . subtract 0.4a

a = 12/0.6 = 20 . . . divide by the coefficient of a

20 L of alfalfa must be added

_____

Check

20/(30+20) = 20/50 = 40/100 = 0.4 . . . . . . answer checks OK