Capital letters that have rotational symmetry are: Z, S, H, N and O. The letters Z, S, H and N, when rotated 180 degrees clockwise or counterclockwise, will look the same after rotation completion.
Do 12-5 then 6.4 then 2.2 then whatever answer you get for 12-5 multiply it by the answer you get for 6.4 then subtract whatever answer you get for 2.2 hope this helps!