Trees grow only on one side of Park Avenue. There are 60 trees in total. Every other tree is a maple, and every third is either a linen or a maple. The rest of the trees are birches. How many birches are there?
Since every other tree is a maple, there are 30 maple trees. And since every third tree is either a linen or a maple, there are 20 linen or maple trees)
Every 6th tree is a maple, so there are 10 maple trees among the 20 (60/6). Therefore, there are 10 linen trees among the 20, and the total number of maple trees is 30.
Since there are 60 trees in total, the number of birch trees is 60 - 30 - 10 = 20.
So there are 20 birch trees in total.