Taxes, discounts, tips and more

Relating Percents to Taxes
A pack of potato chips is priced at $5. If the sales tax in the province is 15%, how much should the potato chips be sold for?
Billy picked a pair of headphones with a selling price of $250 at an electronic store. However, at the check-out counter, he was charged $280. What is the percentage of the sales tax?
Relating Percents to Tips
A family of three went to a five-star restaurant for dinner. The bill for the meal was $180. The family put down $300 and left without asking for changes. In other words, what is the percentage of tips they have paid?
Relating Percents to Discounts
A stationary store is having a garage sale. All the binders priced at $12 are now on sale for $9. What is the discount percentage?
A suit was originally priced at $880, but it has been marked 25% off. What is the selling price now?