The oak tree at school was 34 feet tall then it grew 18 feet taller how tall is the oak tree now

34 + 18
the tree grew 18 ft taller meaning (+18)
add the two numbers to get

52 feet.

Let's use the facts the problem gives us to solve this:

The oak tree began at 34 feet, then grew 18 feet. We must add 18 to the original 34 feet the oak tree began at to find the current height of the tree.

34 + 18 = 52

Now, the oak tree is 52 feet tall. I hope this helps! :)