We discussed, analyzed and solved a geometry-algebra problem involving a real-world application of a linear function. The problem was the construction of a sidewalk around the perimeter of a 10 x 15 ft garden. We let the width of the sidewalk be a variable, sketched the problem on a white board and developed a function of the variable to find the perimeter of the walkway. Ashley immediately recognized the function asa linear function in slope intercept form. We then used the function to explore how increasing the width of the walkway affected its perimeter.