(4/3 -2/5i) + (5/2 +7/4 i) - (4-5i)=
(4/3 - 2/5i) + (5/2 + 7/4i) - (4-5i) =
= 4/3 - 2/5i + 5/2 + 7/4i - 4 + 5i =
= 16/12 - 30/12 - 4 - 8/20i + 35/20i + 5i =
= -14/12 - 4 + 27/20i + 5i =
= - 1 2/12 - 4 + 1 7/20i + 5i =
= -1 1/6 - 4 + 1 7/20i + 5i =
= -5 1/6 + 6 7/20i
