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.

Thank you in advance for your help