posted by tatychass .
if a plane is flying 235 km/h and encounters west wind at 80 km/hr. What's its new velocity?
That depends upon the direction of its initial velocity. You must have left some words and a number out of your question.
Whatever it is, add the two vectors.
The original velocity is not known because the flight direction has not been given.
For example, if it was heading west, the velocity is simply reduced by 80 k/hr to become 153 k/h (ground speed) heading west.