Finding the least common denominator-
What is the smallest number that all denominators can go into? Well I see that the 2/3 has a relation to 5/6. ( 3 * 2 = 6 ).
4 (9/4) does not have a relation to the 6 in 5/6. So, what is the smallest number that 6 and 4 can go into? I see that it is 12. So the answer is 12.
All three numbers, 4, 6, and 3 can go into 12 and 12 is the smallest.