Could really use some help on this!!

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

Mrs. avila is buying a wallpaper border to go on all of her kitchen walls. she wants to buy 5 extra feet of wallpaper border than she needs to be sure she has enough. she buys 55.5 feet of the border. the store owner selling the border uses the width of mrs. avila's kitchen to determine that the length of her kitchen must be 14.5 feet.

Delbert keeps track of total of the total number of points he earns on homework assignments, each of which is worth 60 points. at the end of the semester he has 810 points. write an equation for delbert’s average homework score a in terms of the number of assignments n.