I am starting be re-learn Chemistry after several years.
The Book I am using has a test question to calculate the relative atomic mass of:
$ (CH_3CO)_2O $
My take
Carbon C, $ A_r = 56 $
Hydrogen H, $ A_r = 1 $
Oxygen O, $ A_r = 16 $
$ M_r = ( 56 + 1 \times 3 + 56 + 16 ) \times 2 + 16 = 131 \times 2 + 16 = 278 $
This is nothing like the answer given in the answer key. Is there an error in my text book?
If not where am I going wrong?
Edit: Problem was a misprint in my text book. See correct answer below