The question is in the screenshot

Answer:
b. -36/77
Step-by-step explanation:
As 0 < x < [tex]\pi[/tex]/2 => tan x > 0
As 0< y < [tex]\pi[/tex]/2 => tan y > 0
We have the formula:
As tan x = 1/(cotx) => [tex]tan^{2}x = \frac{1}{cot^{2}x} =\frac{1}{225/64} = \frac{64}{225}[/tex]
As tan x > 0 => tan x = 8/15
As tan y > 0 => tan y = 4/3
As tan (x-y)= [tex]\frac{tan x - tan y}{1+ tanx * tany}[/tex] [tex]=\frac{(8/15)-(4/3)}{1+(8/15)*(4/3)} = \frac{-36}{77}[/tex]