Can someone elaborate on how these are worked out?

Work out Present Value of these, r = 10%

1) $ 250,000 p.a. paid every year for five years with the payment at end of year.

2) $200,000 p.a. for six years with the payment at end of year.

3)$1,250,000 at the end of the fifth year and $1,000,000 at the end of the 10^th year.

4) A $25,000 deposit paid now plus $110,000 p.a. paid forever from the rental of the property. The first $110,000 is paid at the end of the first year.