How to solve this things

Your friend uses c=50p to find the total cost, c, for the people, p, entering a local amusement park is the cost of admission proportional to the amount of people entering the amusement park? explain.

Lowest fraction using common term 28/35

You spend $13 to rent five movies for the weekend. new releases cost $3 and regular movies rent for $2. how many of the movies you rented were new releases and how many were regular movies? answer by substitution of systems.