The price of a halloween costume was reduced from $30 to $12. By what percentage was the price of the costum?

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?

Which compound inequality could be represented by the graph?

Solve for x and y: 217x + 131y = 913; 131x + 217y = 827