Choose your way

From the equations, $x^2=2x$ .
Moving the 2x to the other side, we get $x^2-2x=0$ .
Factoring, we get $x(x-2)=0$ . This tells us x is either 0 or 2 (or both). When x=0, m=0. When x=2, m=4.
Thus, the answer is 2.

Interestingly enough, the pairs are $x=2, m=4$ and $x=0, m=0$ . This is because $x+x$ is the same as $2x$ and $x*x$ is the same as $x^2$ . These graphs intersect at the given points and no others. $m$ represents the y-coordinate of the intersections and $x$ obviously represents the x-coordinate.