Problema Solution
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?
Answer provided by our tutors
Let be x and y the length of the two times
x+y=5
x*105+y*115=555
So 21x+23y=111
If we multiply the first equation with 21 and we subtract it from the second we have:
2y=111-105=6
y=3
x+y=5
x+3=5
x=2
The plane was flown 2 hors with 105 mph and 3 hours with 115 mph