The altitude of an airplane is decreasing at a rate of 44 feet per second. what is the change in altitude of the airplane over a period of 40 seconds?

Aswimming pool has an input pump for filling the pool and an output pump for emptying the pool. the input pump can fill the pool in 3 hours, and the output pump can drain the pool in 5 hours. as you go to bed, the pool is full, but a neighbor’s kid turns on the output pump. at midnight, you awake to find the pool half empty. immediately, you turn on the input pump, but you are sleepy and forget to turn off the output pump. at what time will the pool become full?

How do you use the elimination method for this question? explain, because i really want to understand!

Ijust need these 2 questions answered (the second pic is just confirmation i'm not confident in that answer)