At a restaurant, your food bill was $80$80, and you left a tip of $16$16. what percentage of the food bill did you leave for the tip?

First, we divide the amount of tip which is $16 by the amount that is used to pay the food bill which is $80. Then, multiply the quotient by 100%. Mathematically,
                                        ($16 / $80) x 100% = 20%
Thus, you left 20% of the food bill for the tip.