HOW GO YOU SOLVE THIS WITH STEPS (2+4I)(-4+3I)

Question

THIS IS USING COMPLEX NUMBERS IT IS SECTION 1.3 IN COLLEGE ALGEDRA, i HAVE DONE LIKE FOUR PROBLEM AND i CAN NOT FIRGURE OUT WHAT I AM DOING WRONG.

I WILL DO ONE OF THE PROBLEMS AND SHOW MY WORK.

51. (2+i)(3-2i)= SO I FOIL

6-4i+3i-2i sq.

6-3i

The answer is suppose to be 8-1 how can this be.

Answer 1

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

=-8 -16i +6i +12i*i

=-8 -10i -12

=-20 -10i

or -10(2+i)