I think it is A..............key word:think!
Use arccos...cos^-1 so
cos^-1 (0.8195)
it equals 34.96522689°
The point P has coordinates (x,y) = (-2,6) so x = -2 and y = 6
Replace x and y with those values into the rule given
So,
(x,y) ---> (x-2, y-16)
turns into
(-2,6) ---> (-2-2, 6-16) = (-4,-10)
P = (-2,6)
P ' = (-4,-10)
The answer is -10 because your teacher just wants the y coordinate of point P'