Question 48754
12*15=180 for the garden + 138 for the path or 180+138=318 for the total area 

thus (12+2x)(15+2x)=318 or 180+30x+24x+4x~2=318 or 4x~2+54x-138=0 or using the quadratic equation we get x=2.2 & -15.7 

therefore the path is ~2.2 feet wide

proof (12+4.4)(15+4.4)=318 or 16.4*19.4=318 or 318=318