Your average rate of change for the interval is 3/2 or 1.5, so that should be your answer.
If f(x)=2x-1 just plug in the 3 where x is. So it would be 2(3)-1=5
Answer:
sorry the diagram is not clear......
Simple....
you have:
(-15,70) and (5,10)
Using-->>


Using y=mx+b...and any of the coordinates....
70= -3(-15)+b
70=45+b
70=45+b
-45 -45
25=b
y=-3x+25
Thus,your answer.