Write the point slope form of the equation of the line through (4,3) and (-2,-4)

How do i simply this radical expression?

Monthly water bills for a city have a mean of $108.43 and a standard deviation of $36.98. find the probability that a randomly selected bill will have an amount greater than $173, which the city believes might indicate that someone is wasting water. would a bill that size be considered unusual?

Whats four fifths to the first power