Jamie paid $ 2.50 in library fines using only nickels and dimes. He used more nickles then dimes. How many of each coin did Jaime use to pay the fine

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.