00:01
Here we're given a system of equations and we want to solve it using substitution.
00:05
Well, it's already been put in a great order for substitution because we haven't solved for y already.
00:11
So what i'm going to do is i'm just going to take this y, which is 4x minus 5, and plug it into the original equation.
00:17
So the first equation we have negative 16x plus 4 times y, which happens to be 4x minus 5, and that's equal to negative 20.
00:27
So now we just have to simplify.
00:29
I'm going to negative 16x, and then here we have 4 times 4x is 16, so 16x, and then minus 20.
00:39
When i set this equal to negative 20.
00:42
Now, an interesting thing is happening here.
00:44
We have negative 16 plus 16.
00:46
These cancel away...