Here you need to know and understand order of operations rules, as well as elementary operations on complex numbers.
Remember the acronym "pemdas?" It governs the order in which you must perform math operations. In this case, you must multiply or divide BEFORE you add or subtract. Thus, do -11i*6 first; the correct result (product) is -66i.
Now you have 4 - 66i + 2i. Combining the imaginary terms, -66i + 2i = -64i.
Thus, you end up with 4 - 64i. Any questions?
