What can you multiply an expression by to eliminate the imaginary part of the denominator?

Question

1.) (2+4i)/3i=

2.) (1-2i)/2i=

Answer 1

since in both cases have a monomial as its denominator, all we have to do is mutiply by i/i
I will do the first, you do the second

(2+4i)/i
= (2+4i)/i * i/i
= (2i + 4i^2)/i^2
= (2i - 4)/-1
= 4 - 2i

(remember i^2 = -1)