Question 855152
 A plane took 4 h to fly 2200 km from Saskatoon to 
Toronto with a tail wind. The return trip, with a head wind, took 5 h. Find 
the speed of the plane in still air and the wind speed
***
let x=speed of plane in still air
let c=wind speed
(x+c)=speed of plane with tail wind
(x-c)=speed of plane with head wind
travel time=distance/speed
..
{{{2200/(x-c)=5}}}
{{{2200/(x+c)=4}}}
..
5x-5c=2200
4x+4c=2200
..
20x-20c=8800
20x+20c=11000
add
40x=19800
x=495
5c=5x-2200
5c=275
c=55
speed of plane in still air=495 km/hr
wind speed=55 km/hr