$7.50 meal; 6.5% tax whats the total price?

Use the elimination method to find the solution to the system of equations. 2x - 3y = -9 -x + 3y = 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?

Is this a polynomial function? i need to know asap