I think the answer is 12.9
I had to look for the figure and here is my answer:
Given the circle attached to this question, the area of the sector AOB is the 60 of the fractional part of the area of the circle O. Since the whole circle is 360, this would be 60/360. To simplify this, we would arrive to the final answer of 1/6. Hope this helps.
For this case we have the following equation:

We must clear the value of the variable "x" as a function of r, s and t:
If we multiply by "r" on both sides of the equation we have:

If we subtract "t" on both sides of the equation we have:

If we divide by "2" on both sides of the equation we have:

Thus, the value of the variable "x" is:

Answer:
