the form is
a+bi
a is the real partt
bi is the imaginary part
add complex parts with complex and real with real
treat 'i' as x
remember, i=√-1 so i^2=-1
-2i(9-3i)-1(6-10i)
distribute
-18i+6i^2-6+10i
-18i-6-6+10i
-18i+10i-6-6
-8i-12
-12-8i
answer is -12-8i
