91,007,500 in scientific notation with positive powers of 10

The graph represents the gallons of water in a water tank with respect to the number of hours since it was completely filled

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.

Show your workcan a right triangle have this sides? *how to prove it without using the pythagorean theorema*