10 people can paint a building in 5 days. if each person painted as quickly as the others then how much of the building could 7 people paint in 5 days?

So basically it takes 10 people to paint a whole building. Forget about the 5 days. That's just there to confuse you. You have to first find out how much of a building can one person paint so, 1/10. So that means that 7 people can paint 7/10 of a building in 5 days