So firstly, looking at point P, remember that points follow the (x,y) rule, or (how far left or right from 0, how far up or down from 0). Point P doesn't go left or right from zero, but does go three down, so P's coordinate is (0,-3).
With Point Q, it's the same process. Point Q goes 3 to the right, but doesn't go up or down. Therefore, Q's coordinate is (3,0).
So the vertex is the point in which the parabola is at it's highest or lowest. In this case, because the parabola opens upwards, the vertex is the lowest point. Looking at this line, the vertex is at (1,-4).
Now with the axis of symmetry, it's going to be the same as the vertex's x-coordinate. Looking at our vertex, the x-coordinate is 1. Therefore, the axis of symmetry is x = 1.
