I can't find theta. What am I doing wrong? Easy trig help please! I keep getting it wrong!?

So there is a right triangle with x axis -430.7797 and y axis 152.4342. This means the hypotenuse is 456.9544. It should be easy to find theta, but for some reason I keep getting it wrong. I've done sin^-1 (152.4342/456.9544) and cos^-1(-430/7797/456.9544) and got 19.4866 for both. The answer asks for the angle counter clockwise from the + x axis so I added 180 since the angle is in the 3rd quadrant and got 199.4866. I feel like I know how to do this but I keep getting the answer wrong. Please help! Thank you!!!