What is the rate of change in total sales from month 8 to month 9

Steve wants to develop a way to find the total cost of any item including sales tax. the sales tax in his city is 6%. his friend jenna writes the expression x + 6x where x is the cost of the item. explain whether her expression is correct based on the situation.

Which statement justifies why angle ebc measures 90?

If rt is greater than ba, which statement must be true ?