4 HIKING: At 7:00 A. M., two groups of hikers begin 21 miles apart and head toward each other.
The first group, hiking at an average rate of 1.5 miles per hour, carries tents, sleeping bags,
and cooking equipment. The second group, hiking at an average rate of 2 miles per hour,
carries food and water. Let t represent the hiking time. (Non-anonymous question) * r.

In all honesty, there really is no “work” per say to show. mainly it’s just using the process of elimination. the question is asking which domain(s) would be the most appropriate for the function c(n). n is the number of observed vehicles so right away, 1, 2, and 3 can be eliminated.why? 1, 2 start in the negatives and therefore it is impossible to observe negative cars. so, #4 would be the best answer to the given problem.