Question 1203954
Speed is an example of a rate of change. You may be familiar with the formula

{{{speed = distance/time }}} 

on your graph, you have points ({{{8 }}} ,{{{2 }}} ) and ({{{10 }}} ,{{{5 }}} )

A line through two specific points on a graph is called a secant line. 
In general, the average speed from time {{{a }}}  to time {{{b }}}  is the slope of the secant line through the distance graph at {{{t = a  }}} and {{{t = b }}} .

 the slope of the secant line is:

{{{s=(5-2)m/(10-8)s=(3/2)(m/s)=1.5(m/s) }}} 

the average speed from time {{{8 }}}  to time {{{10 }}}  is {{{s=1.5(m/s) }}}