What is the explicit rule for 2, 0, -2, -4?

The production line where you work can assemble 5 appliers every 30 minutes at this rate how long should it take the line to assemble 125 amplifiers

Bill works as a waiter and is keeping track of the tips he ears daily. about how much does bill have to earn in tips on sunday if he wants to average $22 a day? tips by day tips (dollars) monday tuesday wednesday thursday friday saturday $14 $22 $28 $36

Ineed to know the answer right now! !