You can put this solution on YOUR website! .
In how many ways can 7 boys be seated in a row so that 3 boys are always seated together.
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Please pay attention on how I edited your post to make sense.
It is how a Math problem SHOULD BE.
You actually consider permutations of (7-3+1) = 5 objects "at the upper level" (thinking about these 3 particular boys as one object)
and, in addition to it, you consider all permutations of these 3 particular boys "at the bottom level".
These permutations are independent, so you have, in all
5!*3! = (1*2*3*4*5)*(1*2*3) = 120*6 = 720 permutations. ANSWER
