(3 mark$ 3. An equation used by investigators at accident scenes was introduced in Lesson 1. To determinehe vehicle'sspeedbeforethe collision, investigatormay usethe formula S = 15.9 \\Lf , where 'S is the speedn kilometresperhour of the vehicle 'L' is the lengthof the skid marksin metres and If ' is the coefficientof friction. The skid mark wasleft by the rubbertires on wet asphalt If the speedof the vehiclewas60 km/h and the lengthof the skid markswas28 m, determinethe coefficient' f' . Explainhow you determinethe solutionfrom the graph Makesureto useanappropriate scaleandlabels