15 :)
10.
20
9
4
15
The lowest common denominator needed is 24
10.
20
60
9
15
20
4
3 over 5 and 3 over 4 and 1 over 2
The LCD of 1/2 and 2/3 is 6.
12
If you're wanting to find a common denominator between fractions with denominators of 3 and 2, then 3 & 2 have only a common factor of 1, so the least common denominator = 2*3 = 6