Let us assume the total amount of meal charge paid by Michael without tax = x Then Amount paid to the waiter by Michael = 15x/100 Sales tax paid by Michael = 5x/100 Now we get the equation as x + (5x/100) + (15x/100) = 18 (100x + 5x + 15x)/100 = 18 120x/100 = 18 120x = 1800 x = 1800/120 = 180/12 = 15 dollars So the amount paid by Michael for the meal before tax and tip is $15. I hope the procedure is clear enough for you to understand.
