3 is the answer to your question
The third option is correct.
The answer is 1/6. To solve, simply set up an equation. It will be x/6. As you know, x can stand for anything. 1 will be the reasonable number for variable, x. Why? Well since x=1x. You don't actually write "1" Hope this makes your understanding clear.
M= 2.5 that's the solution for m for them to be equal