Answer:
(Change in y)/(change in x) is defined as the average rate of change.
For a linear equation:
y = a*x + b
A is the average rate of change, and is called the "slope" of the linear equation, and this is a constant.
Then the sentence will be:
"The average change between two ordered pairs (x,y) is the ratio (change in x)/(change in y)
In a linear function, this is called the slope, and it is constant"