Question 1199430
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Dan the Driver travels at 50 km at 80 km/h, 30 km at 60 km/h, and 80 km at 100 km/h. 
Find Dan's average speed in km/h.
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<pre>
The average speed is the total distance divided by the total time

    average speed = {{{(50 + 30 + 80)/(50/80 + 30/60 + 80/100)}}} = {{{160/(5/8 + 1/2 + 4/5)}}} = 

                  = {{{160/((5*5)/40 + 20/40 + (4*8)/40)}}} = {{{160/((77/40))}}} = {{{(160*40)/77}}} = {{{6400/77}}} = 83.169 km/h  (rounded).   <U>ANSWER</U>
</pre>

Solved.