Question

4:18 and 2:12 is that a equivalent ratio

Answer 1

No they are not because if you simplify them as if they were fractions, they aren't.

 4       2
---- = ---
18      9

 2     1
--- = ---
12    6

Answer 2

Well, let's try simplifying 4:18 so we can compare.

If we divide 4:18 by 2, we get 2:9

We can see that 2:9 =/= 2:12
Thus, the two are not equivalent ratios.