Forces of 11.3N north, 19.1N east, and 14.5N south are simultaneously applied to a 4.12kg mass as it rests on an air table. What is the magnitude of its acceleration?

Question

What is the direction of the acceleration in degrees? (Take east to be 0 degrees and counterclockwise to be positive. Enter an angle between -180 degrees and +180 degrees.)

I got 4.70 m/s^2 for the acceleration which is correct. The problem is that I can't find the right angle. I got 9.51 degrees below east (ie. -9.51 degrees) but this is not correct.