Correct. The system that models this situation is $\displaystyle{d}+{c}\le{10}\usepackage{cmbright}\Huge\$ and $\displaystyle{20}{d}+{12}{c}\le{120}\usepackage{cmbright}\Huge\$ . The graph is shown below. Starting at 4 on the d-axis, move up through the region. The highest point for which c is a whole number is (4, 3). This is shown. So Chase can buy at most 3 of the CDs.