How exactly do you connect speakers and monitors to a unpowered mixer?

Can you run 2 speakers and 2 monitors into one mixer?

If so, does the wattage add up for them? For instance if you're sending 500 watts to one side, and you have a speaker there with a wattage of 250 and a monitor their with a wattage of 250 would you be alright?

Thanks for the responses
Quote by progbass
right Metallica is a given. Personally I like to pretend the bus exploded and killed them all in '86.