When finding the least common denominator you look at the denominator of the fraction which is the number below the line.
To find the least common denominator in this question you would find the common multiple of 4,5,and 3
Which ever common multiple shows up first is your answer
Multiples of 4,5, and 3 :
4 8 12 16 20 24 28 32 36 40 44 48 52 56 60
5 10 15 20 25 30 35 40 45 50 55 60 65
3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 48 51 54 57 60
The answer to this problem would be 60