Answer:
point A (6,13) lies on the equation.  True
 given point  B(21,33) lies on the equation.  True
given point  C (99, 137) lies on the equation.  True
The equation that was given was  y = 4/3x + 5
Now,check the given equation for the given points.
1)  A (6,13)
Substitute x = 6 in the given equation y = 4/3x +5
y = 4/3(6) + 5 = 4(2) + 5 = 8+5 = 13
y=13
 the given point A (6,13) lies on the equation.
2)  B  (21,33)
Substitute x = 21 in the given equation y=4/3x+5
y=4/3(21) + 5 = 4(7) + 5=28+5=33
y = 33
 the given point  B(21,33) lies on the equation.
3)  C (99, 137)
Substitute x = 99 in the given equation y = 4/3x + 5
y=4/3(99) + 5 = 4(33) + 5 = 132 + 5 = 137
y = 137
the given point  C (99, 137) lies on the equation.
There is your answer