There could be five in each class.
X could either be 4 or 5, depending on which x the question asks. If you have to chose one answer go with 5 because it's associated with the y.
Distance Formula: 
Point 1: (9,0)
Point 2: (5,-8)
D = sqrt[ (5 - 9)^2 + (-8 - 0)^2 ]
D = sqrt[ (-4)^2 + (-8)^2 ]
D = sqrt[ 16 + 64]
D = sqrt(80)
Hope this helps!