Step 1; Write out the expression
[tex]\begin{gathered} 3+7+2=x+2 \\ \text{where the unknown value is represented by x} \end{gathered}[/tex]Step2: simplify the expression
[tex]\begin{gathered} 12=x+2 \\ \text{collecting like terms} \end{gathered}[/tex][tex]\begin{gathered} x=12-2 \\ x=10 \end{gathered}[/tex]Therefore 10 makes the expression true. C is the correct option