Given that initial speed of two cars u and 4u and final speed v is 0 for both car. Both car is gradually slowing down so acceleration =(−a) So formula becomes, 0=u2−2a s. ⇒u2=2as For first car u2=2as1.....(i) For second car (4u)2=2as2 ....(ii) Dividing (i) and (ii), ‌