A restaurant is open from 9 am to 9 pm on Saturday and a maximum of 90 people are allowed inside. If $f(t)$ is the number of people in the restaurant $t$ hours after 9 am on Saturday, what is a reasonable domain and range for $y = f(t)$? Your answers must be inequalities (not intervals).

Domain: help (inequalities)
Range:   help (inequalities)