distinct object and distinct group group size fixed group sizes are distinct

∴ Total number of ways of division = ¹⁰C₃ × 1 = ¹⁰C₇ × 1
=  
now if we are also to distribute these divided objects into two distinct groups then there are 2! ways to distribute two distinct object into two person
Hence number of ways of distribution  =  × 2!

Example (2).

number of ways of Division = ¹⁰C₂ × ⁸C₃ × ⁵C₅
=   ×   × 
=  

Now these divided packets can be arranged themselves into 3! ways.
Hence number of ways of Distribution =  × 3!