Answer :

To solve a system of equations, you must first set the equations to  equal "y" (which has already been done in this problem), and then set them to equal each other. This can be done because both of your equations equal"y", so they both equal each other.
-2x + 7 = 1/3x
7 = 1/3x + 2x
2 1/3x = 7
x = ~3
The answer is a long decimal with the first four places 0, so I rounded...
Hope that helps:)