So this can be solve by solving the distance of the plane and the town to the west and also the distance of the plane to the town to the east.
So the town with an angle of depression of 34 degrees
Let x be the distance of the plane and town
Cos 34 = x / 8
x = 8 cos 34
x = 6.63 km
So the town with an angle of depression of 49 degrees
Let y be the distance of the plane and town
Cos 49 = y / 8
y = 8 cos 49
y = 5.25 km
so the distance of the towns is 5.25 + 6.63 = 11.88 km