Below is an instruction that describes a task. Write a response that appropriately completes the request in English. Please answer in English.

### Instruction:
Tom plants a tree that is 1 year old and 5 feet tall.  It gains 3 feet per year.  How old is it when it is 23 feet tall?

### Response:
It has gained 23-5=<<23-5=18>>18 feet
So it is 18/3=<<18/3=6>>6 years older
That means it is 6+1=<<6+1=7>>7 years old
#### 7