Question 403108
the 'i' portion is the 'imaginary part'
the 'non-i' portion is the 'real part'

when you have a number with both a real part and an imaginary part, it is called a complex number

the 'real parts' and 'imaginary parts' are orthogonal; that kind of means that they 'exist in their own separate dimensions'

because of that, you can perform addition and subtraction operations on both parts of a complex number independently

we are SUBTRACTING one complex number from another complex number

real part:
-4 MINUS 8 = -12

imaginary part:
3i MINUS i = 2i

so the answer is:
(-12 + 2i)