Two-step equations word problems. Please and thank you in advance!

Which of these tables represents a non-linear function?

The distribution of the amount of money spent by students for textbooks in a semester is approximately normal in shape with a mean of $235 and a standard deviation of $20. according to the standard deviation rule, how much did almost all (99.7%) of the students spend on textbooks in a semester?

Which type of graph would allow us to compare the median number of teeth for mammals and reptiles easily