Ajar contains 30 red, 40 blue, and 50 white buttons. you pick one button at random, find the probability that is not white

Don't know how to find x given these segment lengths

How to use order of operation in 20 divide by 4 multiply 5 = 1

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?