SOLUTION:
First convert the fraction 5/6 so that it has the same denominator as 3/12. To do this, just multiply the numerator and denominator of 5/6 by 2.
So 5/6 is the same as 10/12.
So if you subtract 10/12 minus 3/12 you get 7/12.
So Lea served 7/12 liters more tea than orange juice.
