When given an algebraic expression involving subtraction, why is it best to rewrite the expression using addition before identifying he terms.

There are 12 boy and13 girls in a class. if the teacher randomly chooses a student’s name out of a hat what is the probability it will be a girl

What is the correlation coefficient for the data? don't forget to turn the diagnoisticon (in the catalog menu of the calculator). r = answer (round to the nearest thousandth)

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?