Question 856956
r = normal speed for a trip
t = AMOUNT of time in hours, NOT a point on a time line


___________________speed__________time__________distance
NORMALLY___________r______________t_____________105
START LATE________r+5____________t-1/5__________105


When you understand the sense of the data table, you can continue to solve.


___________________speed__________time__________distance
NORMALLY___________r______________t_____________105=rt
START LATE________r+5____________t-1/5__________105=(r+5)(t-1/2)


The rest of the solution process of solving those two equations for r and t is only slightly tricky.  The "late" equation will have a rt term which can be substituted using the "normally" equation.  Another substitution for one of the variables may also be needed.  You examine the data table and solve the system.