Answer:
439 gallons
Step-by-step explanation:
When the tank is 8 ft, it holds 780 gallons
When the depth is reduced to 4.5 ft, it means 8 ft-4.5 ft=3.5 ft have been sold
Now, if 8 ft represent 780 gallons
3.5 ft represent x gallons used
[tex]x=\frac {780 gallons*3.5 ft}{8 ft}[/tex]
x=341.25 gallons used
x is approximately 341 gallons used
To get the gallons remaining in the tank, we subtract gallons used which are 341 from full capacity which has 780 gallons
Gallons remaining at 4.5ft=780-341=439 gallons