Answer:
50 cars
Explanation:
Let's define p as the number of people and c the number of cars.
We know that p / c = 3/5 or in other words, there are 5 cars every 3 people. If we have 30 people means that p = 30 which implies 30/c = 3/5 which implies c = 5/3 * 30 = 50.