HELP ME PLS (Worth ten points)

2people are trying different phones to see which one has the better talk time. chatlong has an average of 18 hours with a standard deviation of 2 hours and talk-a-lot has an average of 20 hours with a standard deviation of 3. the two people who tested their phones both got 20 hours of use on their phones. for the z-scores i got 1 for the chatlong company and 0 for talk-a-lot. what is the percentile for each z-score?

If cos(2x) = tan^2(y), show that cos(2y) = tan^2(x).

Which expression do you get when you eliminate the negative exponents of 4a^2 b^216a^-3 b