Hey there! I'm happy to help!
We see that an unknown number x multiplied by 12 is equal to 36. How do we find this number? Well, you can simply go backwards and divide 36 by 12, and this will give us our answer.
36÷12=3
Another way you can think about this is dividing both sides of the equation by 12, which isolates our x.
12x=36
12x÷12=36÷12
x=3
Have a wonderful day and keep on learning! :D