## Intermediate Algebra (6th Edition)

$\left[ 3,5 \right]$
Solving the inequalities separately, then, \begin{array}{l} -7x\le-21\\ x\ge3 ,\\\\\text{and}\\\\ x-20\le-15\\ x\le5 .\end{array} Using the conjunction "and", then the solution set is the set common to both inequalities. Hence, the solution set is $\left[ 3,5 \right]$.