[tex]\pink{\mathbb{\underline{QUESTION}}}[/tex]
[tex]{\bf{(9x + 7) + (x + 3)}}[/tex]
[tex]\pink{\mathbb{\underline{SOLUTION}}}[/tex]
[tex]{\bf{(9x + 7) + (x + 3)}}[/tex]
[tex]{\bf{\implies9x + 7 + x + 3}}[/tex]
[tex]{\bf{\implies9x + x + 7 + 3}}[/tex]
[tex]{\bf{\implies10x + 10}[/tex]
Hence, 10x + 10 is answer.