r + s means you add the two equations together, so you get 1 + 2i + 3 + 3i
Treat the numbers with i like variables, so they can’t be added to the whole numbers, but they can be added to each other without changing the value of i.
Add everything together, by personal preference I do whole numbers first, so it would be (1 + 3) + (2i + 3i) = 4 + 5i.
