I need help with this. Thanks

I need to find the degree

  119.05°

Step-by-step explanation:

In general, the angle is given by ...

  θ = arctan(y/x)

Here, that becomes ...

  θ = arctan(9/-5) ≈ 119.05°

Comment on using a calculator

If you use the ATAN2( ) function of a graphing calculator or spreadsheet, it will give you the angle in the proper quadrant. If you use the arctangent function (tan⁻¹) of a typical scientific calculator, it will give you a 4th-quadrant angle when the ratio is negative. You must recognize that the desired 2nd-quadrant angle is 180° more than that.

__

It may help you to consider looking at the "reference angle." In this geometry, it is the angle between the vector v and the -x axis. The coordinates tell you the lengths of the sides of the triangle vector v forms with the -x axis and a vertical line from that axis to the tip of the vector. Then the trig ratio you're interested in is ...

  Tan = Opposite/Adjacent = |y|/|x|

This is the tangent of the reference angle, which will be ...

  θ = arctan(|y| / |x|) = arctan(9/5) ≈ 60.95°

You can see from your diagram that the angle CCW from the +x axis will be the supplement of this value, 180° -60.95° = 119.05°.

the answer is 31.27mph