Answer
The solution is between 12 and 13.
Work Step by Step
$\underline x\ \ \ \ \underline{6x+5}$
$10\ \ \ \ \ \ 65$
$11\ \ \ \ \ \ 71$
$12\ \ \ \ \ \ 77_{\longrightarrow}$ the solution is between 12 and 13
$13\ \ \ \ \ \ 83$
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