How do you find the solution of the system of equations #3x + 6y = 18# and #2x + 5y = 20#?
You just need to isolate
Now, we replace this found
Now, you just replace this
(There are other possible ways, for example using matrixes or subtracting one equation from another, but I would only recommend that in case you have MORE than two variables. The resolution I posted appears to be the simplest).