Add 84.0393 and 231.6581 and round the sum to the nearest hundredths and thousandths​

I uploaded the answer to a file hosting. Here's link:

tinyurl.com/wtjfavyw

the answer is (4,3)

since the rule for r0, 90º is (-y,x) and it was already applied to form the image, all you have to do is reverse the answer using this formula.