Answer:
B
Explanation:
if you multiply m by 2 you get 260we now want to subtract this from 360 to get 100 then we divide that by 2 to get angle n∠BEF= 50°.
We know angle k∠EBF= 90° so we now end up with adding angle ∠BEF with ∠EBF to get 140 to get angle x we subtract 140 from 180 to get 40. x=40°. so B is the correct answer