I want to know the answer to his question

ok, maybe you really don't know how to do this, but this is just being plain lazy. any way,
see the B's that have a little 2 on them? image that the other B's also have the same thing, but it's a one.
[tex]{b}^{2} + {b}^{1} + {b}^{2} + {b}^{1} [/tex]
see all the numbers above the B's? add them all
[tex]2 + 1 + 2 + 1[/tex]
And you get 6
now take one of your Bs and slap the six on like so
[tex] {b}^{6} [/tex]
and there's your answer