Please help o need to know the slope!

Consider the functions below. function 1 function 2 function 3 select the statement which is true about the functions over the interval [1, 2] a b function 3 has the highest average rate of change function 2 and function 3 have the same average rate of change. function and function 3 have the same average rate of change function 2 has the lowest average rate of change d.

What is the missing step in this proof ?

Can someone me with the property questions for 12 13 and 14 plz