SOLUTION: I am struggling to understand the rules that cause this type of problem to be solved as it is: (8.7 + 3.1i) + (6.8 - 7.1i) + (5.4 + 4.1i) As per our textbook, the correct com

Question 878041: I am struggling to understand the rules that cause this type of problem to be solved as it is:
(8.7 + 3.1i) + (6.8 - 7.1i) + (5.4 + 4.1i)
As per our textbook, the correct combined solution looks like:
(8.7 + 6.8 + 5.4)+ (3.1 - 7.1 - 4)i
I understand everything except for the " - 4" term. All of the other terms are taken directly in their correct positive and negative form from the original problem, whereas the 4 has switched from positive to negative. I don't understand why.
Answer by Fombitz(32388) (Show Source): You can put this solution on YOUR website!
Yes, that's incorrect.
It should be

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