I just need help on questions 7, 8, 9, 12, and 13

For question 7, I keep thinking that the pool area is a square, so wouldn't all sides be equally fenced? Therefore wouldn't the 25M be equally divided by 4 to maximize area?

http://i238.photobucket.com/albums/f...hmwrk_0001.jpg

http://i238.photobucket.com/albums/f...hmwrk_0002.jpg

Thank-you in advance :)