To find the range, subtract the least value from the greatest value: $\displaystyle{65}-{15}={50}\usepackage{cmbright}\Huge\$ .

To find the midrange, add together the least and the greatest values and divide by 2: $\displaystyle\frac{{{65}+{15}}}{{2}}=\frac{{80}}{{2}}={40}\usepackage{cmbright}\Huge\$

The range is 50 and the midrange is 40.