A gardener plants a row of eight trees chosen from three maples, two oaks, and four birches. In how many ways can he plant the row if: trees of the same type have to be adjacent?

18

Step-by-step explanation:

each possibility needs to exclude one tree so:

mmoo is when you exclude a maple

mmmo is when you exclude an oak

mmmoobbb is when you exclude a birtch

then you can mix them up to get 6 ways per exclusion

6x3=18

so 18 is your answer!

1) is right

step-by-step explanation: