2/15+1/15=3/15 which isn't less than a half
2/15+8/30=2/15+4/15=6/15 which isn't less than a half
2/15+5/15=7/15 which isn't less than a half
and 2/15+8/15=10/15 which is greater than a half, and when cancelled down is 2/3 which is definitely greater than a half:)
