Since ABCD is a rectangle, the sides AB and AD are perpendicular.
The slopes of perpendicular segments or lines have the following relation:
![m_2=-(1)/(m_1)](https://img.qammunity.org/2023/formulas/mathematics/college/famfci9sb6car80iseo3b973mc71ztg8tq.png)
The equation for the line AB is in the slope-intercept form: y = mx + b.
Therefore we can identify its slope: m1 = 2/3.
Now, calculating the slope m2 of line AD, we have:
![m_2=-(1)/((2)/(3))=-(3)/(2)](https://img.qammunity.org/2023/formulas/mathematics/college/6zf8kas3vlp1qt8sl995a53v8nu4mty8xe.png)
Therefore the slope of line AD is equal to -3/2.