The answer to this question would be: 4 different ways
It will be easier to answer this question by making a list of the possible way. In this question, the group is either 10 rocks or single rock. Then the list should look like this:
1. 3 groups of 10 rocks + 8 groups of single rock
2. 2 groups of 10 rocks + 18 groups of single rock
3. 1 groups of 10 rocks + 28 groups of single rock
4. 0 groups of 10 rocks + 38 groups of single rock
