3. Solving Word Problems

A smartphone originally costs \$800 but is now sold for \$680. Calculate the percent discount.

A reservoir's water level decreased by $20\%$ over the summer due to evaporation. If the water level is currently at $120$ million liters, how much water was there initially?

Carson bought some new sneaker on sale for $\$250$. The sale price was $65\%$ of the original price. What was the original price?

The bookstore buys a set of novels for \$120 and sells it for \$150. What percent did they mark up?

If sales tax on a \$36 pair of shoes is \$1.26, find the sales tax on a $\$250$ pair of shoes.