## Thinking Mathematically (6th Edition)

$\left\{ x\le 11 \right\}$.
Let us suppose the number is $x$. Then, the algebraic form of the inequality is: $3\left( 5+x \right)\le 48$ And now to find out possible values of $x$ satisfying the inequality the inequality is solved as follows: \begin{align} & 3\left( 5+x \right)\le 48 \\ & 5+x\le 16 \\ & x\le 11 \end{align} Hence all the real numbers less than or equal to 11 will satisfy the condition. The set-builder form of the inequality obtained is: $\left\{ x|x\le 11 \right\}$ The set-builder notation for all real numbers that satisfy the given condition is$\left\{ x\le 11 \right\}$.