How should I write this sentence better?
I would like to write

They both weren’t mature enough at twenty, an age that most people expects you to have matured up.

It seems odd to me how I expressed it. could anyone
show me how I can make it better?

Question

How should I write this sentence better?
I would like to write

They both weren’t mature enough at twenty, an age that most people expects you to have matured up.

It seems odd to me how I expressed it. could anyone 
show me how I can make it better?

Answer

Ohh, yes these are so much better.  I didn’t know “mature up” wasn’t a word, and I should really start using “neither” more.  Zak and Irene thanks a lot!

Answer

Hi Rou! Maybe something like:

Neither of them were that mature at twenty, an age when most people expect you to have grown up.

you can say: 
-to grow up
-to become mature 
 
but you can't say: 
to mature up

hope that helps :)

Answer

Neither of them were mature enough by the age of twenty.  By that age you are expected to have grown up.

لا تفوّت فرصة تعلّم لغة جديدة وأنت مرتاح في منزلك. تصفّح مجموعتنا المختارة من مدرّسي اللغات ذوي الخبرة وسجّل في درسك الأول الآن!