Answer:
45 gallons
Step-by-step explanation:
1 hour = 3 gallons
2 hours = 6 gallons
3 hours = 9 gallons
4 hours = 12 gallons
5 hours = 15 gallons
10 hours = 30 gallons
15 hours = 45 gallons
4315
<u>+5684
</u> 9999 So 5684 is the greatest number you can write.<u>
</u>