The left graph is a two dimensional graph of the equation y = x.

When x = 3, then y = 3.

The point on the line of the equation is at (x,y) = (3,3). That would be 3 units to the right on the x-axis and 3 units up on the y-axis from the point (x,y) = (0,0).

The right graph is a three dimensional graph of the equation z = x + y.

When x = 2 and y = 2, then z = 4.

The point on the plane is at (x,y,z) = (2,2,4). If the intersection of the axis grids were at the point (x,y,z) = (0,0,0), then that would be 2 units forward on the x-axis, 2 units right on the y-axis, and 4 units up on the z-axis.

Since the intersection of the axis grids is at the point (x,y,z) = (-5,-5,-5), then some adjustment needs to be made in order to find the point (x,y,z) = (2,2,4).

The adjustment is relatively easy to make. You simply add 5 to the number of units that need to be traveled in each direction from the point (-5,-5,-5). The point (2,2,4) is therefore 7 units forward in the direction of the x-axis, 7 units to the right in the direction of the y-axis, and 9 units up in the direction of the z-axis.