Donte simplified the expression below.

4(1 + 3i) – (8 – 5i) = –4 + 8i

what mistake did donte make?
a. he did not apply the distributive property correctly for 4(1 + 3i).
b. he did not distribute the subtraction sign correctly for 8 – 5i.
c. he added the real number and coefficient of i in 4(1 + 3i).
d. he added the two complex numbers instead of subtracted.

The answer is: [A]: He did not apply the distributive property correctly for                                        4(1 + 3i) .

Explanation:

Note the distributive property of multiplication:

a*(b+c) = ab + ac.

As such: 4*(1 + 3i) = (4*1) + (4*3i) = 4 + 12i ;

Instead, Donte somehow incorrectly calculated:

4*(1 + 3i) = (4*1) + 3i = 4 + 31; (and did the rest of the problem correctly);

Note:  - (8 - 5i) = -8 + 5i (done correctly; 

So if Donte did not apply the distributive property correctly for 4*(1+3i)—and incorrect got 4 + 3i (as mentioned above); but did the rest of the problem correctly, he would have got:

4+ 3i - 8 + 5i = -4 + 8i (the incorrect answer as stated in our original problem.

This corresponds to: "Answer choice: [A]: He did not apply the distributive property correctly for 4(1 + 3i)."