Time value of money calculations can be solved using a mathematical equation, a financial calculator, or a spreadsheet. Which of the following equations can be used to solve for the present value of an ordinary annuity?

PMT/r

PMT x {1 [1/(1 + r)nn]}/r

PMT x {[(1 + r)nn 1]/r}

PMT x {[(1 + r)nn 1]/r} x (1 + r)

Not finding this in my book, googling isn't helping either. Equations like this are really confusing for me, any help is greatly appreciated.