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.
