Im confused on the bottom circle answer its a bit weird it reads "a. (use algebra) Use the diagram at the right. What algebraic expression represents GK? b. if GK = 30, what are GH and JK?"

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