The coordinates of the midpoint if the endpoints are (x₁,y₁) and (x₂,y₂):

One endpoint is (3,5), the midpoint is (5,-11). The other endpoint is (x,y).

The coordinates of endpoint M are (7,-27).
Proportion A
The first thing you should know in this case is what the rate of change means.
The rate of change in a linear equation is given by the slope of the line.
For a linear equation, the rate of change is constant.
So we have to:
y = 9x
The slope is:
m = 9
Proportion B
The slope of the line will be:
m = (y2-y1) / (x2-x1)
Substituting values:
m = (57.5-34.5) / (5-3)
m = 11.5
Answer:
The rate of change in proportion A is 2.5 less than in proportion B.
Your answer would be C) 12
equation: 1,124.94 - 200.10 / 77.07 = 12