# Math Help - Word problem:

1. ## Word problem:

I'm having difficulties setting this equation up. Can someone help me?

Question:

How many gallons of milk that is 10% butterfat must be added to 8 gallons of milk that is 35% butterfat to obtain milk that is 20% butterfat?

2. Originally Posted by thumpin_termis
I'm having difficulties setting this equation up. Can someone help me?

Question:

How many gallons of milk that is 10% butterfat must be added to 8 gallons of milk that is 35% butterfat to obtain milk that is 20% butterfat?
Hello,

let x be the number of gallons of milk with 10% butterfat.
For confirmation only: 10% = 0.1 and 35% = 0.35

Then you know:

$0.1x + 0.35 \cdot 8 = 0.2(x+8)\ \Longleftrightarrow \ 0.1x + 2.8 = 0.2x + 1.6$

$1.2 = 0.1x \Longleftrightarrow x = 12$

So you have to add 12 gallons of milk with 10% of butterfat.

3. Wow, it just seems so easy once you explain it. Thanks a bunch!