Please help me with math!

Tiara buys the pizza shown below: a circular pizza is shown. the edge of one slice is marked ab. what does the curve ab represent?

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?

A50% increase followed by 33 1/2% decrease