When subtracted, what is the simplified form of (5 − 3i) − (4 + 6i)? write the answer in standard form, a + bi, where a and b are real numbers.

(5 - 3i) - (4 + 6i)      Remove the brackets. Be careful with those on the right.
5 - 3i - 4 - 6i            Did you notice how the second set worked. That - sign affected both terms inside the brackets. Now collect your like terms.

5 - 4 - 3i - 6i   The - 3i and - 6i  act like money. You are three dollars in the hold and you spend another 6. Where does that put you ?
1 - 9i              You are now 9 dollars in the whole.