Question 87389
1. Thomas left Miami and drove at a speed of 41 mph. Katherine left 1 hour and 28 minutes later and drove at a speed of 57 mph. How long will it take Katherine to catch up with Thomas?

----Step#1: try to visualize the problem.  Drawing may help.
Basically it is asking at what point is Katherines distance equal to Thomas.

Drawing example:
|==============================> Thomas's distance is 41*Time
|**************************> Katherine's distance is 57*(Time-1hr 28min)

So, 57*(T-88/60) = 41T
57T-83.6 = 41T
16T = 83.6
T = 5.225hr = 5hr 13.5min
So, it took Katherine (5hr 13.5min) - (1hr 28min) = 3hr 45.5min

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2. EdHelper Airlines flight H3488 from Boston to Dallas averaged a speed of 90 mph more than the return trip back to Boston. The return trip took 1 109/308 times longer than the trip going to Dallas. The distance between Boston and Dallas is one thousand, seven hundred fifty miles. What was the average speed from Dallas to Boston?
---Step#1:List 2 conditions:

B-->D:
speed = 90+S
time =T

D-->B:
speed = S
time = (1 109/308)T

----Step#2:  Distances are the same

so B-->D = D-->B
becomes (90+S)T = S(1 109/308)T          ---Note the T's cancel out)
becomes 90+S = S(1 109/308)
becomes 90 = (109/308)S
becomes 90(308/109) = S
becomes S = 27720/109  --------(from your posting I'm not sure what the units are so not sure if it mph or km/hr)