Answer:
There are 4200 ways
Explanation:
The number of ways in which n elements can be organized in k groups is calculated as:

Where n is the number of elements and
are the number of elements of each group.
In this case, we have 10 people to create 3 groups, one with 4 people, and two groups with 3 people. So, n is equal to 10, k is equal to 3,
is equal to 4,
is equal to 3 and
is equal to 3.
Then, replacing the values, we get:

So, there are 4,200 ways to divided 10 people into three groups.