Question

The pilot of a plane measures an air velocity of 165 km/h south. An observer on the ground sees the plane pass overhead at a velocity of 129 km/h toward the north.
What is the velocity of the wind that is affecting the plane? Let north be positive.
Answer in units of km/h

Answer 1

36 km/h south

Answer 2

165-129

Answer 3

That's what I thought, but when I submitted it, it was wrong. Is it supposed to be negative?

Answer 4

Yes, it should be negative since the wind is to the south.

Answer 5

Thank you!