Solution: Suppose the number of people involved in tree planting is X, and the number of trees planted by each person is Y as originally planned.

6x=0.75xy

1.5xy=xy+40

So 8=y

0.5xy=40，x*8=80

Therefore, x= 10. Therefore, A: The number of people who participated in tree planting was 10, and the original plan was to plant 8 trees per capita.

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