00:01
So in this problem, we're helping peppermint patty out in a peanuts cartoon.
00:05
And it says that she has some cream, or she wants to know how many gallons of cream at 25 % butterfat, and how many gallons of milk at 3 .5 % butterfat needed to be blended together to make 50 gallons at 12 .5 % butterfat.
00:22
So let's make x be the gallons of cream.
00:31
And we'll let y be the gallons of milk.
00:40
Well, then we know that x plus y has to be 50, because i'm making 50 gallons.
00:50
And then with the butter fats, we can say 0 .25x, because it's 25 % butterfat, plus 0 .035y, that's 3 .5%.
01:04
A 1 .5 % would be 0 .5, and then we'll do the percentage into decimal.
01:09
We'll move the decimal in two places.
01:11
Okay.
01:12
Is 50 times 0 .125, 12 .5%.
01:19
Okay.
01:21
So i'm going to call this equation 1 and that equation 2.
01:26
So from equation 1, i have that x is 50 minus y...