How do i find x in this question. i'm very confused.

The depth of a lake at a certain point, wich is a function of the distance of that point from shore, is 30 feet.

() at a farm, animals are fed bales of hay and buckets of gain.each bale of hay is in the shape of a rectangular prism.the base side lengths 2 feet and 3 feet,and the height is 5 feet. each bucket of grain is a cylinder with diameter of 3 feet. the height of the bucket is 5 feet as the height of bale. a. which is larger in area, the rectangular base of the bale or the circular base of the bucket? explain how you know b. which is larger in volume, the bale or the bucket? explain how you know

Eric has challenged himself to walk 24,000 steps in 4 days. if eric walks the same number of steps each day, which function represents the number of steps eric still needs to walk to reach his goal with respect to the number of days since he started his challenge? a. y = 8,000x − 24,000 b. y = -8,000x + 24,000 c. y = 6,000x − 24,000 d. y = -6,000x + 24,000