If anyone is good at ratios, please help

Describe the 2 algebraic methods you can use to find the zeros of the function f(t)=-16t^2+400.

If, while training for a marathon, you ran 60 miles in 2/3 months, how many miles did you run each month? (assume you ran the same amount each month) write your answer as a whole number, proper fraction, or mixed number in simplest form. you ran __ miles each month.

What is the 17th term in the arithmetic sequence in which a6 is 101 and a9 is 83