Leila wrote an equation to represent the revenue of a parking lot for one day. she let x represent the number of cars that paid to park and y represent the number of trucks that paid to park. if a car costs $8 per day, a truck costs $10 per day, and the total revenue for the day was $830, which equation could leila use to represent the number of cars and trucks that paid to park that day?

David is spreading mulch on a triangular area of his flower bed. the coordinates of the vertices of the area are (1, 3), (9, 3), and (4, 6). what is the area of the triangle if each square has an area of 3 square feet?

How many revolutions will a car wheel of diameter 28 in. make over a period of half an hour if the car is traveling at 60 mi/hr? the final answer is supposedly 21,609 but i have no idea how to get that, show work : )

Julius went on a volunteer trip to centralamerica and took medical supplies with him. he packed a bag with 50 pounds of supplies. he brought pieces of equipment that weighed10 pounds each and bottles of medicine thatweighed pound each prepresents thenumber of pieces of equipment he broughtand b represents the number of bottles ofmedicine he brought then the total weight canbe represented by the equation 10p+b 50.the brought 3 pieces of equipment, how manybottles of medicine did he bring?