I don't know how to even start to work on this problem what should i consider.

To solve the problem, we need to set up an equation based on the information given.

Let's denote the length of the mountain trail as "x" miles. Since two-thirds of the total distance of 10 miles is over the mountain trail, we can say that (2/3) * 10 = x.

Now, the equation becomes:

(2/3) * 10 = x

We can simplify this equation as:

20/3 = x

So, the mountain trail is 20/3 miles long.

Now that you have the equation, you can solve it by simplifying and calculating the value of x. In this case, the mountain trail is 20/3 miles long.