Which expression can go in the blank to make the equation true? 60 – 31.2 + ? = 0 a. 60 – 31.2 b. -60 + (-31.2) c. 31.2 - 60 d. 60 - (- 31.2)

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?