Correct. Mr. Simpson tips at least $\displaystyle{\left(\ge\right)}\usepackage{cmbright}\Huge\$ 10% of the bill, which comes to (0.1)($100) $\displaystyle=\usepackage{cmbright}\Huge\$ $10, and at most $\displaystyle{\left(\le\right)}\usepackage{cmbright}\Huge\$ 20% of the bill, which comes to (0.2)($100) $\displaystyle=\usepackage{cmbright}\Huge\$ $20. The inequality to be represented should be $10 $\displaystyle\le{d}\le\usepackage{cmbright}\Huge\$ $20.