# What's the least number of car parked?

In a car park, there are 2 white car for every 3 blue cars and for every 2 blue cars there are 5 silver cars. What is the least number of cars in the park?

I am a bit confused about my approach to the question, according to my thinking...

But I still think that I am making a wrong approach. Need help.

• I thought this was a simple question, but so far you have four different answers: $20$, $25$, $30$ and $36$. – Henry Jan 21 '14 at 18:19
If there are $w$ white cars, $b$ blue cars and $s$ silver cars then you know $$\frac{w}{2} =\frac{b}{3},$$ $$\frac{b}{2} =\frac{s}{5}.$$
If you are not allowed fractions of a car or striped cars, then $b$ must be a multiple of $3$ and a multiple of $2$, which means $b$ is a multiple of $6$. If $b=6$ then $w=4$ amd $s=15$ making a total of $25$ cars.