We have the following:
[tex]3+7+2=x+2[/tex]
Now, for this to be true we must look for a number that makes the sum of both sides equal, as follows
[tex]\begin{gathered} 3+7+2=x+2 \\ x=3+7 \\ x=10 \\ \text{then} \\ 3+7+2=10+2 \\ 12=12 \end{gathered}[/tex]
Therefore, the number that makes the equality true is 10
