we draw a picture
red line is the Rob's road traveled 6ft, 6ft and diagonal
we can calculate the diagonal using pythagoras because the shape of the walk is a right triangle

where a and b are legs of the triangle and h the hypotenuse, replacing the values of the legs

simplify

and solve for diagonal
![\begin{gathered} d=\sqrt[]{72} \\ d=6\sqrt[]{2} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/xk49qper3szb08nf3h7sct13v1irvvqd3u.png)
now sum the walked sides
![\begin{gathered} 6+6+6\sqrt[]{2} \\ =12+6\sqrt[]{2}\approx20.5 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/c2suxxvrhr0bh06zblt35owlgiz6zgswk6.png)
Rob walks 20.5 feet