Ali , Bob , Cid travel from Town Y to Town Z in a straight road .

They leave Town Y at the same time and travel at constant speed towards Town Z .

Ali drives a car at speed of 56 km/h .

Bob jogs at a speed of 8 km/h .

Cid walks at a speed of 7 km/h .

At the start , Ali gives a lift to Bob from Town Y and drops Bob somewhere along the road to Town Z before returning to pick up Cid and travel to Town Z .

All three of them arrived at Town Z at the same time .

If Bob had jogged for 2.8 km , how far did Cid walk ?