You first start with adding the number in the parentheses,because none of them can add in this equation it stays the same:
(3x^2 + 3) + (3x ^2 + x + 4)
Since there is nothing that we can do while there are parenthaseese we remove them:
3x^2 + 3 + 3x ^2 + x + 4
Next add the x^2’s:
6x^2 + 3 + x + 4
Lastly the normal numbers:
6x^2 + 7 + x
Now that there are no more numbers that are the same, 6x^2 + x + 7 is your simplified equasion.
Hope this helps! :)