To express the given numbers as the rectangular form of a complex number, we'll have to perform the additions and subtractions of like components of the complex number. That means that we'll combine the given real parts and the imaginary parts.
(2-5i)-(-4-5i) = 2 - 5i + 4 + 5i
We'll eliminate like terms and we'll have:
(2-5i)-(-4-5i) = 6
We'll put the result in the requested form:
(2-5i)-(-4-5i) = 6 + 0*i
We'll transform the second number:
(-3i)-(7-4i) = -3i - 7 + 4i
We'll combine the imaginary parts:
(-3i)-(7-4i) = -7 + i
Therefore, the requested complex numbers, expressed in the form a + bi, are: (2-5i)-(-4-5i) = 6 + 0*i and (-3i)-(7-4i) = -7 + i.