Answer:
[tex]\frac{23}{8}\text{ gallons used on the two days}[/tex]Step-by-step explanation:
The total of gallons used by Justin on the two days would be the sum of the gallons of gas used on Sunday and on Monday:
[tex]2\frac{3}{4}+\frac{1}{8}=\frac{23}{8}\text{ gallons of gas}[/tex]