Given:
Total capacity if tank is 12 gallons.
Percentage of fuel filled in the tank is, 75%.
It is given that 75% of 12 gallons tank is filled.
Then, consider the gallons of filled as x.
[tex]\begin{gathered} \frac{75}{100}\cdot12=x \\ x=\frac{75\cdot12}{100} \\ x=\frac{900}{100} \\ x=9 \end{gathered}[/tex]Hence, the gallonos of gas fuel filled in tank is 9 gallons.