What is (3/4)^-2 and how do i express it as a positive?

Three coins are flipped. what is the probability that there will be at least two tails?

Find and simplify an expression for the area of five rows of x squares with side lengths of x centimeters.

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?