Answer:

Step-by-step explanation:
Here, we want to calculate the value of x without using a calculator
We have to look for the quadrants where the tan is negative
These are the second and the fourth quadrant
On the second quadrant, we have the reference angles as:

Mathematically in degrees:

Now, on the second quadrant, we have it that:

On the fourth quadrant, we have the reference angle calculated as:

Lastly, we have to convert these angles to radians
Mathematically, 1 pi is 180 degrees:
