Explain how to multiply the complex #'s (3+2i)(4-i)

Multiply the numbers like you multiply binomials.
Multiply every term of the first binomial by every term of the second binomial.
Then combine like terms, and remember that i^2 = -1.

(3 + 2i)(4 - i) =

= 12 - 3i + 8i - 2i^2

= 12 + 5i + 2

= 14 + 5i