Answer:
60 kph
Step-by-step explanation:
The relation between time, speed, and distance is ...
time = distance/speed
speed = distance/time
distance = speed × time
___
Jack's plane flies at a speed of ...
(52 km)/(0.2 h) = 260 km/h
If the wind speed is represented by w in km/h, then the distance remaining (in km) is ...
(distance there) - (distance covered in 3.5 h) = 100 km
(260 +w)(2.5) - (260 -w)(3.5) = 100
-260 +6w = 100
6w = 360
w = 60
The wind speed was 60 km/h.
_____
Check
The distance going was ...
((260 +60) km/h)(2.5 h) = 800 km
The distance covered in 3.5 hours coming back was ...
((260 -60) km/h)(3.5 h) = 700 km . . . . . 100 km short of the destination
