+1439 I have $4$ different mathematics textbooks and $3$ different psychology textbooks. In how many ways can I place the $7$ textbooks on a bookshelf, in a row, if all the psychology textbooks are together?
+297 You can refer to the above question as a hint, but ill leave the solution below.
consider the psychology books as one unit. so the total ways is 5!/4!, 5! because there are 5 different units, and 4! because the math books are indistinguishable. (Im assuming), so the answer is 5
