Question 551178
The horse galloped m miles at p miles per hour and then trotted m miles at k miles per hour.
 What was the average speed for the entire trip?
:
let a = the average speed of the entire trip
:
{{{m/p}}} + {{{m/k}}} = {{{(2m)/a}}}
:
{{{(mk+mp)/(pk)}}} = {{{(2m)/a}}}
Cross multiply
a(mk+mp) = (pk*2m)
a = {{{((2pkm))/((mk+mp))}}}
cancel out m
a = {{{((2pk))/((k+p))}}} the average speed for the entire trip