Tamara uses a coupon to save 20% off her purchase at the bookstore. The original cost of Tamara's purchase is d dollars. Which expressions represent the cost, in dollars, of Tamara's purchase after using the coupon? Choose all that apply.

Acompany that manufactures and sells guitars made changes in their product range. from the start they had 20 models. then they reduced the number of models to 15. as a result, the company enjoyed a 10% increase in turnover. - how much did the stock level change? in (%)

Awater tank holds 18000 gallons. how long will it take for the water level to reach 6000 gallons if the water is used at anaverage rate of 450 gallons per day

Gabrielle's age is two times mikhail's age. the sum of their ages is 84. what is mikhail's age?