2out of 15 cars are blue. how many cars are blue when there are 225 cars

Lets figure this out...
The starting ratio is 2:15. We need a new ratio with 225 cars. Let b represent the number of blue cars.
2:15=b:225
Divide 225 by 15. You should get 15. That means each side of the original ratio needs to be multiplied by 15.
2x15=30
15x15=225
So, the new ratio is 30:225.
There are 30 blue cars. 
Hope this helps : )

I’ll you if you answer my questions!