combs

[demoskopico]

There are 3 red chips and 2 blue ones.
When arranged in a row, they form a certain color pattern, for example RBRRB. How many color patterns?

10
12
24
60
100

I tought it was 5C2* 5C3. Why is not like that?

[kevin]

You chose 2 of the 5 places for blue chips. Don't the 3 remaining places automatically get red ones?

[demoskopico]

You chose 2 of the 5 places for blue chips. Don't the 3 remaining places automatically get red ones?

sometimes I definitely get confused with perms and combs...I know the rules but don't know when to apply them!