9.30 A gardener has to plant 10 trees over the course of three days. In how many ways can he distribute the work over the days, if he will plant no less than one tree per day
9.30 Let's separate the trees designated for planting on each day with boundaries. There are two such boundaries, and there are 9 possible places for them (the number of intervals between ten trees). We have $C_{9}^{2}=36$.

Answer: 36 ways.