I can't see the diagram sorry.
Step-by-step explanation:
Is there supposed to be a picture attached?
 
        
             
        
        
        
Answer:
do you have to add the numbers together or multiply
 
        
                    
             
        
        
        
Answer: 
...
against the wind, an airplane travels 3640 km in 7 hours.
with the wind, the same plane travels 6000 km in 6hrs.
...
let speed of plane in still air be x mph
speed of wind be y mph.
..
t=d/r
..
against wind speed = x-y mph
with wond speed = x=y mph
...
3640/(x-y)=7
3640 = 7x-7y 
/7
520=x-y.....................1
...
6000/x+y = 6
6000 = 6x+6y
/6
1000=x+y.....................2
...
Add (1) & (2)
2x=1520
/2
x=760 mph speed of plane in still air
...
plug value of x in 2
1000=760+y
100-760=y
240 = y
240 mph speed of wind