Answer:
1 : 4
Explanation:
Set up the ratio like this...
150 : 600 (150 cars to 600 minivans)
Now reduce....
Both numbers end with a zero, so divide by 10..
15 : 60
Both numbers are multiples of 15, so divide by 15....
1 : 4
The ratio of cars to minivans is 1 : 4