Question 877094
The standard form looks like 
a + bi.

Post one question at a time or else no one will reply.

I will do (5 - 7i)(-4 - 3i).

Use FOIL method to expand. 

5(-4) = -20
5(3i) = 15i
(-7i)(-4) = -28i
(-7i)(-3i) = 21i^2

We have -20+15i-28i+21i^2.

Remember i^2 = -1

-20-13i+21(-1)

-20-13i-21

Answer: -41-13i