SOLUTION
(1) We want to add
[tex]\begin{gathered} x+3x+5+2 \\ x\text{ means 1}x \\ \text{adding we have } \\ 4x+7 \end{gathered}[/tex]Hence, the answer is 4x + 7
(2)
[tex]\begin{gathered} 4s-2s+10 \\ =2s+10 \end{gathered}[/tex]Hence, the answer is 2s + 10
(3)
[tex]\begin{gathered} n+n+7+n+4 \\ we\text{ place the n's together and the numbers together, we have } \\ n+n+n+7+4 \\ \text{This also means } \\ 1n+1n+1n+7+4 \\ =3n+11 \end{gathered}[/tex]Hence, the answer is 3n + 11