Hello,
This is straaaaaaaaaaaaaange
90=arctan(x/16)+arctan(x/200)
If we compose with tan, we have :
tan(90)=tan(arctan(x/16)+arctan(x/200))
But tan(90)= infinity :'(
We can find somewhere the general formula for tan(a+b). I haven't looked further, maybe there is a solution though.