Question

which ratio is equal to 4:9

Answer 1

8:18, 12:27, 16:36, etc

Answer 2

just to let you know, in case you didn't already...ratios can be written as fractions.
Example : 2:3 = 2/3 , 4:9 = 4/9 , 3:4 = 3/4

so basically your are just looking for an equivalent fraction to 4/9.
you can find an equivalent fraction by multiplying numerator and denominator by the SAME NUMBER.

4/9 * 2/2 = 8/18 which can also be written like 8:18
4/9 * 3/3 = 12/27 which can be written like 12:27

Its that simple :)