In looking at it I would guess it is asking which of the points is on the line? To answer that you would have to take each point an plug it into the equation and see if it is true.
3x - 7 = y
A(9,20)
3(9) - 7 = 20
27 - 7 = 20
20 = 20 True - this point is on the line
B(5,0)
3(5) - 7 = 0
15 - 7 = 0
8 = 0 False - this point is not on the line
C(3,2)
3(3) - 7 = 2
9 - 7 = 2
2 = 2 True - this point is on the line
I hope this helps
The line of the equation perpendicular to y=5 and cuts through (-5,-7) will be given by
m(x-x1)=y-y1
where m=slope.
from y=0x+5, the slope of the perpendicular line m=0,
thus the equation will be:
0(x--5)=y--7
0=y+7
y=-7
The equation is y=-7
Answer: 
for number 7
Step-by-step explanation:
a²+b²=c²
3²+8²=c²
9+64=c²
