Try subtracting the second equation from the first: write $(x + 2y) - (x - y)$ on the left and subtract the right-hand sides as well. What variable disappears?

Once you find the value of $y$, plug it into either $x + 2y = 11$ or $x - y = 5$ to solve for $x$, which is what the question asks for.

In Desmos, type x + 2y = 11 on one line and x - y = 5 on another. Desmos will graph both lines on the coordinate plane.

Look for the point where the two lines intersect. Tap or click on that intersection; Desmos will display its coordinates $(x,y)$.

From the intersection coordinates shown by Desmos, note the $x$-coordinate. That is the value of $x$ that solves the system.

The system is

Notice that the coefficient of $x$ is 1 in both equations. If you subtract the second equation from the first, the $x$ terms will cancel out:

Now simplify the left side and right side of the equation from Step 1:

So the value of $y$ in the solution is 2.

Use either original equation with $y = 2$ to find $x$. Using $x - y = 5$:

Therefore, the value of $x$ in the solution to the system is $7$.