00:01
Given the following system of equations, we need to solve it by using substitution.
00:06
So the second equation, x equals 4.
00:10
Y minus 10 is going to replace the x in the first equation.
00:14
So the equation is going to become negative 2.
00:16
Instead of x, we're going to replace it with 4y minus 10 plus 5y is equal to 5.
00:26
Y is only in the equation, so the substitution is good.
00:29
So we're going to distribute.
00:29
You get negative 8y plus 20 plus 5y is equal to 5.
00:35
Then we combine like terms.
00:37
You get negative 3y plus 20 is equal to 5.
00:41
Move the 20 over, and you get negative 3y is equal to negative 15.
00:47
Divide both sides by negative 3, and you get y is equal to positive 5.
00:51
To find the value of x, you replace the y in the x equals equation with 5.
00:56
So you get 4 times 5 minus 10...