The problem asks us to select all ratios that are equivalent to the ratio $3:12$.

1. Problem Description

The problem asks us to select all ratios that are equivalent to the ratio $3:12$.

2. Solution Steps

First, simplify the given ratio $3:12$. Both numbers are divisible by 3, so dividing both by 3 gives:

$3/3 : 12/3 = 1:4$

Now we need to check each of the given ratios to see if they simplify to $1:4$.

Ratio 1: $2:8$

Both numbers are divisible by 2, so $2/2 : 8/2 = 1:4$. Thus, $2:8$ is equivalent to $3:12$.

Ratio 2: $8:9$

This ratio cannot be simplified further. Also, $8/9$ is not equal to $1/4$. Thus, $8:9$ is not equivalent to $3:12$.

Ratio 3: $14:18$

Both numbers are divisible by 2, so $14/2 : 18/2 = 7:9$. Also, $7/9$ is not equal to $1/4$. Thus, $14:18$ is not equivalent to $3:12$.

Ratio 4: $7:28$

Both numbers are divisible by 7, so $7/7 : 28/7 = 1:4$. Thus, $7:28$ is equivalent to $3:12$.

3. Final Answer

The ratios equivalent to $3:12$ are $2:8$ and $7:28$.