00:01
I'm given the following system, and we need to solve it using substitution.
00:05
So we're already given x equals 9, so that 9 is going to replace the x in the second equation.
00:11
So when we write the second equation, it becomes 9 minus 3 equals 6y plus 12.
00:18
So we're going to clean up the left hand side, so that becomes 6, 6y plus 12.
00:24
We move the 12 over by subtracting, so we get negative 6 is equal to 6y.
00:28
We divide both sides by 6, and we get negative 1 is equal to y.
00:34
We already know that the x value is 9.
00:36
So the solution to the system is 9 negative 1.
00:40
But we need to make sure and check it by plugging in the solution back into the original problems...