Question 1155855
<pre>
                SPEED      TIME        DISTANCE

Was doing         40         2         40*2=80

Next hour         r          1           r

TOTALS                       3          r+80
</pre>

Want average speed , 50 mph.

{{{(r+80)/3=50}}}

-

{{{r+80=150}}}

{{{r=150-80}}}

{{{r=70}}}