Question

What is the x-coordinate of the solution of the following system of equations?

Answer 1

The easiest way to solve this is by elimination. 

3x - y = 6 

6x + y = 21

Since you have a negative and positive y with the same coefficients (1), they cancel, and you add the other terms so it would look like:

9x = 27 

Then solving for x leaves you with x = 3 

Then you take the x value of three and plug it into to either of the equations, so 

3(3) - y = 6

9 - y = 6 

subtracting 9 

-y = -3 

then dividing by -1 

y = 3 

so the solution is x = 3 y = 3 or (3,3)