We have `2 tan^(-1) (tan x) = 6 -x`
or `tan^(-1) (tan x) = (6 - x)//2`
To find the number of solution, we draw the graphs of `y = tan^(-1) (tan x) and y = (6 -x)/(2) " or " x + 2y - 6 = 0` as shwon in the following figure.
From the figure number of solution is three