I'm back again and still not understanding quadratic equations. My assignment has 4 questions and I answered the first 3 but I am stuck on number 4, which is a multi-question (a, b, c, & d) word problem. I would like someone to check my work on numbers 1 - 3, 4a, 4b, and help me to understand 4c and 4d of the word problem.

http://i3.photobucket.com/albums/y63.../Algebra/1.jpg

http://i3.photobucket.com/albums/y63.../Algebra/2.jpg

http://i3.photobucket.com/albums/y63.../Algebra/3.jpg

http://i3.photobucket.com/albums/y63.../Algebra/4.jpg

http://i3.photobucket.com/albums/y63.../Algebra/5.jpg

http://i3.photobucket.com/albums/y63.../Algebra/6.jpg

http://i3.photobucket.com/albums/y63.../Algebra/7.jpg

http://i3.photobucket.com/albums/y63.../Algebra/8.jpg

http://i3.photobucket.com/albums/y63.../Algebra/9.jpg

http://i3.photobucket.com/albums/y63...Algebra/10.jpg

http://i3.photobucket.com/albums/y63...Algebra/11.jpg

Thank you in advance for your help