Jessica drank 1/8 gallon of orange juice

And what else you can not solve that problem

1/8+1/3. The denominator is changed to 24. 1/8 will turn to 3/24 and 1/3 will turn to 8/24. 3/24+8/24= 11/24.

Okay, to first find how many the two drank you have to add the fractions together. The lcm of 8 and 3 is 24,

1/3 x 8/8 =8/24
1/8 x 3/3 = 3/24

so you add 3/24 and 8/24, which gets you 11/24 gal, [c]

To do this problem make both of them have the same denomnator. Try to find the smallest number by seeing the smallest multiple 8 and 3 have in common. This would be 24 since thats the smallest number they have in common.
For 1/8 to get 24 in the denominator multiply top and bottom by 3 to get 3/24
For 1/3 to get 24 in the denomnator multiply top and bottom by 8 to get 8/24
We need 24 in both denominators to add them became same denominators allow us to add the numerators
3/24 + 8/24=11/24 since 8+3=11 in the denominator 
The answer is c