Question

Which ratio is equal to 6/15?

Answer 1

The greatest common factor between 6 and 15 is 3.
You can reduce 6/15 down to 2/5.

Answer 2

: A ratio obtained by multiplying or dividing the numerator and denominator of a given ratio by the same number is called an equivalent-ratios. 

 Consider the ratio 6 : 4,
6/4 = (6 x2)/(4 x 2) = 12/8 
6/4 = (6 x3)/(4 x 3) = 18/12 
6/4 = (6 x4)/(4 x 4) = 24/16 
And so on.
All these are equivalent-ratio of 6/4.
If a : b and c : d are two equivalent-ratios, we write a/b = c/d 

1) Find two equivalent-ratios of 6 : 15.
Solution : 
6/15 = (6 x2)/(15 x 2) = 12/30 
6/15 = (6 ÷ 3)/(15 ÷ 3) = 2/5 
So, 12 : 30 and 2 : 5 are the two equivalent-ratios of 6 : 15.

Here is an helpful video
https://www.youtube.com/watch?v=CamClJACdAI