TITLE: If $u = 2 + 3i$ and $v = -5 + 4i$, then $u + v =$?
QUESTION [5 upvotes]: I have an exercise, it says:
If $u = 2 + 3i$ and $v = -5 + 4i$, then $u + v =$ ?
My answer: $$u + v = (2 - 5) + (3 + 4)i = -3 + 7i$$ 
but the correct answer is $7 - 3i$.
What is wrong with my solution?

REPLY [2 votes]: We sum real and imaginary parts thus
$$2+3i-5+4i = -3+7i$$
There must be a typo in your study material.