00:01
Let's say we have a total of $12 ,000 that we want to invest.
00:07
A part of that, we can invest at 10%, and the remainder we can invest at 15%.
00:15
So total, whatever the amount of one plus the other is going to equal that 12 ,000, but we also want the 10 % amount plus the 15 % amount to total 12 % amount to total 12 % of our full investment.
00:40
So 12 % of this 12 ,000.
00:45
So we want to figure out how much of each percentage we need to invest in order to come out to this 12%.
00:52
So let's go ahead and just rewrite these as decimals instead of percentages.
00:57
So i'm going to go ahead and say this is 0 .1x plus 0 .15y equals now 12 % times 12 ,000, that's 0 .1 ,000.
01:12
1 2 times 12 ,000, i'm going to go ahead and simplify that as 1 ,440.
01:20
Now, how i go about solving this, thinking about the substitution method, i can solve for one of these variables, let's say x and all that means is i'm subtracting y on both sides.
01:33
This becomes x equals 12 ,000 minus y.
01:39
And i'm going to substitute that for the x down here.
01:42
This becomes 0 .1 times 12 ,000 minus y plus 0 .15y equals that 1440...