Which ratio is not equivalent to the other three? A. 2/5 B. 12/15 C. 6/15 D. 18/45

Lets do equal fractions by multiplying and dividing them by a number:

(2/5) (3/3) = 6/15

= (6/15) (3/3) = 18/45

so these are equivalent:

2/5 = 6/15 = 18/45

The fraction 12/15 is not equivalent to them, because there is no number that multiplying and dividing it gives the others.