To find an equivalent ratio of \( 12 : 36 \) in the form \( x : 3 \), we first simplify the ratio \( 12 : 36 \).
- Divide both parts of the ratio by 12: \[ 12 \div 12 : 36 \div 12 = 1 : 3 \]
Now, we have the simplified ratio \( 1 : 3 \), which means that \( 12 : 36 \) is equivalent to \( 1 : 3 \).
Since we want the ratio to be in the form \( x : 3 \), we observe that in the ratio \( 1 : 3 \), the second part is already 3. Therefore \( x = 1 \).
Thus, the equivalent ratio of \( 12 : 36 \) as \( x : 3 \) is: \[ x = 1 \]
So, \( x : 3 = 1 : 3 \).