8x² - 4x=0 - factoring

How many sides does a regular polygon have if each exterior angle measures 72a.3b.4c.5d.6

Monthly water bills for a city have a mean of $108.43 and a standard deviation of $32.09. find the probability that a randomly selected bill will have an amount greater than $155, which the city believes might indicate that someone is wasting water. would a bill that size be considered unusual?

Ihave trouble finding the nth term of a linear sequence