



 
Hi Jamal, I can help get you started. I would start by letting the distance travelled on good surface be $x$ kilometers. Then ask how long the man travels on good surface? To answer this invert the speed he travelled on these roads to see 72 kilometers per hours as $\large \frac{1}{72}$ hours per kilometer. Does this help?  


Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences. 