A human factors expert recommends that there be at least 9 square feet of floor space in a college classroom for every student in the class. Find the minimum space that 18 students require

X/y + 4y/x divided by x/y - 2y/x explain as in depth as you can how you simplfied the fractions. i don't know where to start on this : /

Arestaurant offers delivery for their pizzas. the total cost the customer pays is the price of the pizzas, plus a delivery fee. one customer pays $23 to have 2 pizzas delivered. another customer pays $59 for 6 pizzas. how many pizzas are delivered to a customer who pays $86?

Deena is planting two rectangular gardens. one garden is 3.67 feet by 8.56 feet, and the other garden is 3.67 feet by 7.45 feet. which expression does not respresent the total area in square feet of the two gardens