Why is 85 a composite number?!

Which of the following is most likely the next step in the series? a3z, b6y, c9x, d12w, е15v, f18u

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.

Write the fraction 9/50 as a decimal if needed round to the nearest hundredth