Any smart cookie help me answer this optics/focal length question?

[ilovegeeks]

I'm really stuck, I've been doing questions all day so I think my poor brain is just a bit frazzled. Any help will be much appreciated!<br style="color: rgb(51, 51, 51); font-family: arial, helvetica, clean, sans-serif; font-size: 13px; line-height: 16px; "><br style="color: rgb(51, 51, 51); font-family: arial, helvetica, clean, sans-serif; font-size: 13px; line-height: 16px; ">Thanks for all your time

https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-ash4/417804_235689599847986_100002208446841_502821_1921907877_n.jpg

[dimreepr]

I'm really stuck, I've been doing questions all day so I think my poor brain is just a bit frazzled. Any help will be much appreciated!<br style="color: rgb(51, 51, 51); font-family: arial, helvetica, clean, sans-serif; font-size: 13px; line-height: 16px; "><br style="color: rgb(51, 51, 51); font-family: arial, helvetica, clean, sans-serif; font-size: 13px; line-height: 16px; ">Thanks for all your time

https://fbcdn-sphoto...921907877_n.jpg

 

 

I may be really thick but what exactly is your question?

[swansont]

I'm really stuck, I've been doing questions all day so I think my poor brain is just a bit frazzled. Any help will be much appreciated!

 

What have you got so far? What equation(s) might apply here?