A 555-mile, 5-hour plane trip was flown at two speeds. For the first part of the trip, the average speed was 105 mph. Then the tailwind picked up, and the remainder of the trip was flown at an average speed of 115 mph. For how long did the plane fly at each speed?

• A 555-mile, 5-hour plane trip was flown at two speeds.
  For the first part of the trip, the average speed was 105 mph.
  Then the tailwind picked up, and the remainder of the trip was flown at an average speed of 115 mph.
  For how long did the plane fly at each speed.
  :
  Let t = time flown at 115 mph
  the total time is 5 hrs therefore:
  (5-t) = time flown at 105 mph
  :
  Write a distance equation; dist = speed * time
  :
  115mph dist = 105mph dist = 555 mi
  115t + 105(5-t) = 555
  
  
  115t + 525 - 105t = 555
  115t - 105t = 555 - 525
  10t = 30
  t = 30%2F10
  t = 3 hrs at 115 mph
  then
  5-3 = 2 hrs at 105 mph
  :
  :
  Check this by finding the actual dist at each speed
  115*3 = 345 mi
  105*2 = 210 mi
  --------------
  total: 555
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