Answer:
He still needs to fill 79.43% of the tank.
Explanation:
How much of the tank he filled?
1 3/4 gallons
As a decimal number, this is:
Conversion to liters:
1 gallon has 3.785 liters.
So, for 1.75 gallons, we have 1.75*3.785 = 6.62 liters.
The fish tank holds 32.176 liters.
So, he still needs to fill 32.176 - 6.62 = 25.556 liters.
What percentage of the tank does he still need to fill?
We divide what need to be filled by the total capacity, and multiply by 100. So
He still needs to fill 79.43% of the tank.