Question 766841
Let x = time in hours for the 60 mph trip.


PLEASE NOTE: Time units for this table are in hours.  There are 60 minutes in 1 hour; 40 minutes is 40/60 hours, or 2/3 hour.


TRIP____________speed______time___________distance
Actual___________60________x______________60x
Hypothetical_____50_______x+40/60_________50(x+2/3)


The distances are equal.
{{{highlight(60x=50(x+2/3))}}}
Solve for x, in hours.  Change result to minutes or mixed units if desired.



------
{{{3&1/3}}} hours, 3 hours and 20 minutes.
-
EDIT:  Knowing {{{x=3&1/3}}} hours, we can find distance of the trip, {{{60x=60*3&1/3=highlight(200)}}} miles.