For this case, the first thing we must do is define variables:
p: plane speed
w: wind speed
With the wind in favor, the speed is:
[tex]p + w = 1920/2
[/tex]
With the wind against the speed is:
[tex]p - w = 1920 / 3.2
[/tex]
Rewriting both equations, we have the following system of equations:
[tex]p + w = 960
p - w = 600[/tex]
Then, solving the system of equations (graphically for example), we have the solution is:
[tex]p = 780
w = 180[/tex]
Therefore, jet stream's speed:
[tex]w = 180 km / h
[/tex]
Answer:
A) p + w = 960; p - w = 600; jet stream's speed = 180 km / h