1) let x = time it would take to fill up the the pool

2) x/21 + x/18 + x/24 = 1

3) x/21 + x/18 + x/25 = 1/1

4) 9450x/21 + 9450x/18 + 9450x/25 = 9450

5) 450x + 525x + 378x = 9450

6) 1353x = 9450

7) x = 9450/1353

8) x = 6.9 which means 6 hours and 54 minutes (or rounded, 7 hours)

Sorry I couldn’t do number 2. I’ll try working on it.

you first need to find out at what rate each one fills at. for example… i don’t know how much water you need but i based it on 10,000 gallons… so

18hrs=10,000 gallons (10,000/18=555.5 gallons/hr)

21hrs=10,000 gallons (10,000/21=476.2 gallons/hr)

24hrs=10,000 gallons (10,000/24=416.6 gallons/hr)

add all together

555.5

+

476.2

+

416.6 = 1448.3 gallons / hr

now

divide 1448.3 gallons/ hr by 10,000 gallons

for a final time of 6.9 hrs

2) ok, the answer is impossible. if one person needs at least $5, and the amounts need to be equal, then 5*8=40, not 30. ( i did guess and check)

your welcome!