What is the simple subject And simple predicate in this sentence

If you need one, then buy a cell phone

the simple subject is "if you need one"

and the simple predicate is "then buy a cell phone"

Explanation:

The simple subject is "if you need one" because it only tells the beginning.

The simple predicate is "then buy a cell phone" because it is at the end and doesn't tell why should you buy a cell phone!

your welcome!