To start off, we need 20 percent of a value of the purchase, x, to be equal to 5 dollars (as you get 5 dollars off in one, and get 20% off in the other. In addition, x must be over 10 dollars, making our equation 20 percent of x=5. As 100 percent of x is our goal (to find the total value of x), we can multiply both sides by 5 (as 100/20=5) to get 100 percent of x = 25. Therefore, the total bill is 25 dollars.
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