Answer:
equation: C = 40P
cost for 13 people: 520 dollars
Explanation:
each person needs to pay $40, so we know that our C will be directly proportional to P where each P costs 40 dollars ( C = 40P )
we have 13 people so we replace the variable P with 13 ( C = 40(13) )
we multiply 13 by 40 and end up with C = 520, so we know that will be the cost for 13 people