You can find a common denominator using the two denominators multiples.
1.3x-2.39=5.76x+4.74
+2.39 +2.39
_________________
1.3x=5.76x+7.13
-5.76x -5.76x
______________
-4.46x=7.13
/-4.46 /-4.46
__________
x=-1.6
D
I think it would be C since two right angles both have a total of 90 degrees. So if u were to add the two angels u would get 180