How do you solve this math problem?

Question

h= -8t^2+40t

then it says:
when t=0 and when t= 5

there are 2 questions that i have to answer:

1.) find the value of h

2.) graph this equation

- i don't know if i did the problem right but when i answered #1 i got h=0,
- and when i answered #2 the 8 and y coordinates that i was supossed to point were too high, like (1,32), (2,48,), (3, 48), etc. but our graph only goes up to 15-20, so either i did it wrong, or I need to know how to change the interval values on the a ti-84 graphing calculator

~ so just show me how to solve each problem, and if you have to change the intervals tell me what buttons to press! thanks so much!

Answer 1

1. is correct
2. not sure, sorry