Aballoon drifts 140m toward the west in 45s ; then the wind suddenly changes and the balloon flies 90m toward the east in the next 25s. what distance did it travel during the first 45s?

140 m

Explanation:

Let's begin by stating clear that motiont is the change of position of a body at a certain time. So, during this motion, the balloon will have a trajectory and a displacement, being both different:

The trajectory is the path followed by the body, the distance it travelled (is a scalar quantity).  

The displacement is the distance in a straight line between the initial and final position (is a vector quantity).  

So, according to this, the distance the balloon traveled during the first 45 s (its trajectory) is 140 m.

But, if we talk about displacement, we have to draw a straight line between the initial position of the balloon (point 0) to its final position (point 90 m).  Being its displacement 95 m.