24.6+3a/4=9.54 what dose a = and give me work

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?

Jordan got 27 out of 90 correct on his test . what fraction of the marks did her get correct

Matt had 5 library books. he checked out 1 additional book every week without retuening any books. whats the matching equation