You may have thought that secant was the reciprocal of sine, but it is the reciprocal of cosine. Also, you need to use the definitions of sine and cosine together with the given values to find the sides of a right triangle that would have those ratios. A triangle with $\displaystyle{o}{p}{p}={8}\usepackage{cmbright}\Huge\$ , $\displaystyle{h}{y}{p}={17}\usepackage{cmbright}\Huge\$ , and $\displaystyle{a}{d}{j}={15}\usepackage{cmbright}\Huge\$ will have those ratios. Use this information and the definition to find the value of tangent.