Question 712328
 A car travels along a straight line at a constant speed of 62.5 mi/h for a distance d and then another distance d in the same direction at another constant speed.
 The average velocity for the entire trip is 32.5 mi/h.
:
Let s = "another constant speed"
:
Write a time equation; time = dist/speed
:
1st dist time + 2nd dist time = total time
{{{d/62.5}}} + {{{d/s}}} = {{{(2d)/32.5}}} 
Multiply equation by 2031.25s (62.5*32.5),results:
32.5sd + 2031.25d = 62.5(2sd)
32.5sd + 2031.25d = 125sd
divide thru by d
32.5s + 20321.25 = 125s
2031.25 = 125s - 32.5s
2031.25 = 92.5s
s = {{{2031.25/92.5}}}
s = 21.96 ~ 22 mph 0n the 2nd d
:
:
Check this using d = 100, see if it is true
{{{100/62.5}}} + {{{100/22}}} = {{{(200)/32.5}}}