Answer: Scroll down to find out :)
Explanation:
a) To solve t^2 - 82t + 160 = 0, we can factor it.
I got (t - 2)(t - 80) = 0, so t is either 2 or 80. So it begins in 2 secs and ends in 80 secs.
b) To find the vertex, we need to do (-b/2a), (substituting -b/2a in the equation). That gives us (82/2), (41^2 - 82*41 + 160) = (41, -1521)
So, the vertex is (41, -1521)
P.S. I tried my best lol, sorry if it isn't right.