What is the distance between points (9, -4) and (9,4) on the coordinate plane

For f(x)=2x+1 and g(x)= x^2 -7, find (f•g)(x)

Find the distance between the point (-3,-4), and (see the picture below)

Last week , donnell practiced the piano 3 hours longer than marcus . together, marcus and donnell practiced the piano 11 hours . for how many hours did each young man practiced the piano