How do find the slope of more than one point when you have to estimate to graph the points

Tabby sells clothing at a retail store, and she earns a commission of 6.25% on all items she sells. last week she sold a pair of jeans for $32.50, a skirt for $18.95, and 2 blouses for $14.95 each. what was tabby's total commission? a $4.15 b $5.08 c $81.35 d $348.60

The standard deviation for a set of data is 5.5. the mean is 265. what is the margin of error?

Abox holds 500 paperclips. after a week on the teacher's desk 239 paperclips remained. how many paperclips were used?