What are the real and imaginary parts of the following complex numbers: i) -3 - 4i, ii) 20 + 4i, iii) -1 - 2i, iv) 4 - i?

The real part is the term without $i$.
The imaginary part is the coefficient of $i$.
Real part: $\boxed{-3}$
Imaginary part: $\boxed{-4}$

Real part: $\boxed{20}$
Imaginary part: $\boxed{4}$

Real part: $\boxed{-1}$
Imaginary part: $\boxed{-2}$

Note that $-i$ is equivalent to $-1i$.
Real part: $\boxed{4}$
Imaginary part: $\boxed{-1}$