Answer: 225 cars.
Step-by-step explanation;
Think of it this way: there are 3 cars for every 2 trucks. So, if they are 150 trucks, how many cars are they? We can find this by first finding the multiple (150/2), the multiple is 75. Then multiply the multiple with the common ratio for cars, (75*3), this will be 225. So, if there are 150 trucks, then they are 225 cars.