The are 8 blue bicycles, 6 green bicycles, and 4 yellow bicycles and total they equal 18.
You can't factor it at all
the pattern goes as adding 3 then subtracting with 1,
1+3=4
4-1=3
3+3=6
6-1=5
so its like that now we have to continue it like:
5+3=8
8-1=7
so the pattern goes like 1,4,3,6,5,8,7