What is the missing fraction?

With this question! what is process of elimination? ? p. s. my brothers acc got banned so add his new one @ yamauchiyamyam17

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

Reduce fractions expressing probability to lowest terms. in 3,000 repetitions of an experiment, a random event occurred in 500 cases. the expected probability of this event is?