15 dollar tip is 20 percent of the total cost of dinner. what is the total coast of diner

The answer is 90 dollars because 15/ 20%= 75, which you then add on the 15 dollars you had to divide by and you then get 90$ in total.

c.

step-by-step explanation:

because first you have to add the 4x, 9x, and the 7x together and you get 20x and then you add the last numbers up and you get 5and then you put the subtraction sign in there and that's how you get the answer.