Which of the following functions is not linear?

Samantha swam upstream for some distance in one hour. she then swam downstream the same river for the same distance in only 12 minutes. if the river flows at 4 mph, how fast can samantha swim in still water?

Consider circle h with a 3 centimeter radius. if the length of minor arc what is the measure of zrst?

Write the expression in complete factored form. 5n_(c - 3) - n(c - 3) =