You can
put this solution on YOUR website! .
if tan(x)/x = -2 , then x = ?
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This equation is not algebraic.
It is transcendental and can not be solved algebraically.
It only can be solved numerically and only approximate solution can be obtained.
For this purpose, special solvers are developed.
One of such solvers is at this web-site
https://mathworld.wolfram.com/TranscendentalEquation.html
Print your equation there 
= 0
and get the solution quickly x = -33.00187236... radians (rounded).
Solved.
