Answer:
the average airspeed of the plane = 42 miles per hour
the average wind speed = 12 miles per hour
Step-by-step explanation:
Let x be the average airspeed of the plane.
Let y be the average wind speed.
Distance =time * speed
Initial trip:
Return trip: 
We solve for x and y
Multiply both sides by 3
54= x+ y
y= 54- x ------------> equation 1

Multiply both side by 5
90 = 3(x-y)
90= 3x- 3y ------------------> equation 2
Plug in y=54-x in second equation
90= 3x- 3(54-x)
90 = 3x - 162 + 3x
90 = -162 + 6x
Add 162 on both sides
252= 6x
Divide both sides by 6
So x= 42
y= 54- x
Plug in 42 for x
y= 54 - 42= 12
the average airspeed of the plane = 42 miles per hour
the average wind speed = 12 miles per hour