Okay, here we have this:
Considering the provided information, we are going to identify wich equation applies, so we obtain the following:
[tex]x+19=2x[/tex]
Where x represents the uknown number. Then finally we obtain that the correct equation is the third one.
Now, let's find the missing number solving the equation:
[tex]\begin{gathered} x+19=2x \\ 19=2x-x \\ 19=x \end{gathered}[/tex]
Finally we obtain that the number is equal to 19.
