Explanation for the first question attached in image
Also note - The converse of the hinge theorem states that if two triangles have two congruent sides, then the triangle with the longer third side will have a larger angle opposite that third side.
6*1.20 is the cost in dollars per 100 kilometers. If each friend pays for one third (666.66 repeating kilometers), then they would have to pay (6*1.20)*6.66 repeating which equates to $48 per person and $144 total.