Express (4 - 5i)(5 + 5i) in the form a + bi, where a and b are integers and i^2 = -1.
(4 - 5i ) ( 5 + 5i) =
4*5 + 4*5i - 5i * 5 - 5i * 5i =
20 + 20i - 25i - 25i^2 =
20 - 5i - 25 (-1) =
20 - 5i + 25 =
45 - 5i
