Respuesta :
[tex]\huge\text{Hey there!}[/tex]
[tex]\mathsf{9a + 3 + 4 + (3a + 1)}\\\mathsf{= 9a + 3 + 4 + 3a + 1}}\\\text{COMBINE the LIKE TERMS}\\\mathsf{= (9a + 3a) + (3 + 4 + 1)}\\\mathsf{= 9a + 3a + 3 + 4 + 1}\\\mathsf{= 12a + 7 + 1}\\\mathsf{= 12a + 8}\\\\\\\huge\text{Therefore, your answer should be: } \\\huge\boxed{\mathsf{12a + 8}}}\huge\checkmark[/tex]
[tex]\huge\text{Good luck on your assignment \& enjoy your day!}[/tex]