Question 328358
let the speed of superprop plane be x mph
the turbo speed will be x+50 mph
..
distance traveled by superprop = 2800
time taken by superprop = 2800/x
..
the turbo travels a distance of 2000 miles
speed = x+50 mph
time = 2000/x+50

Time taken by superprop - time taken by turbo = 3 hours
2000/x-2800/(x+50)= 3
LCM = x(x+50)
2000(x+50)-2800x/ x(x+50)=3
2000x+100000-2800x=3x(x+50)
-800x +100000= 3x^2+150x
3x^2+950x-100000=0
find the roots using quadratic formula 
x1=83.33mph speed of superprop
x2=-400 ignore
speed of turbo = 83.33 + 50= 133.33 mph