100 points: how do you find the derivative to solve the integral?

For each proportion find the unknown number x 1/5/8=×/15

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?

Write the sine and cosine values of a, b, respectively, in the figure for (1) and (2) + explanation.