Find the circumference of a circle with a diameter of 6 cm. leave your answer in terms of π

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

[10 points, algebra 2]according to my answer key the restrictions are -1 and 4. but why not positive 1?

y=2x−1 5x−4y=1 is (1,1)(1,1) a solution of the system?