Someone please help explain how to find x.

The exterior angles of any polygon will always add up to 360 degrees. Since we know all the values for every exterior angle, we can simply make the following equation:

3x + (x + 50) + 4x + (2x + 40) = 360

Simplify:

10x + 90 = 360
10x = 270
x = 27

If you want me to explain anything I did here, just ask :)

-T.B.

4hours and 40 mins she would be 120 meters high