Question 1058472
Fifteen minutes is same as {{{(1/4)hour}}}.

<pre>
             RATE         TIME      DISTANCE
FIRST        2/t            t          2
LAST         2/(t+1/4)     t+1/4       2
AVERAGE      3.2
Total                    t+(t+1/4)     4
</pre>


AVERAGE rate given as 3.2, and the rate for the average is  the distance divided by the time; the TOTALS.


{{{highlight(4/(t+(t+1/4))=3.2)}}}