00:01
In this problem based off of a peanuts comic, we are dealing with some amount of cream, c, and some amount of milk, m.
00:07
This is going to be in gallons.
00:09
Now, we know that the total amount in a mixture between cream and milk should be 50 gallons.
00:14
So c plus m should equal 50.
00:17
Additionally, we want a certain fat content in our final product.
00:21
That is, we want it to be 12 .5 % fat in 50 gallons.
00:25
So the amount of fat will be 12 .5 % in decimal form, that is, 0 .1 .1 .2%.
00:30
125 times 50 gallons.
00:32
I convert that percent to a decimal by moving the decimal point over two spots to the left.
00:37
We know that cream is 25 percent fat and we know that milk is 3 .5 percent fat.
00:46
Thus we can have an equation something like this.
00:49
0 .25 times c plus 0 .035 times m equals 0 .125 times 50.
00:55
This is just determining the total fat content in the cream plus total fat content in milk equals total fat content in the mixture.
01:04
Now we've got two equations, two variables, so we can solve.
01:07
Let's get started.
01:08
The first thing that i'm going to do here is multiply out this 0 .125 times 50, which, when multiplied, will give us 6 .25.
01:18
Now, i'm going to do something that might look a bit strange here, but i'm going to multiply this top equation by negative 0 .25 on both sides...