If 3cot........

  3 cotθ= 5

 to find   5 sin  θ --- 3   cos  θ    /  4 sin  θ  +  3   cosθ

 dividing through out by  sinθ  numerator & dinominator  , 5  -- 5  cosθ/sinθ    / 4   +  3 cos θ / sinθ

                                                                                                        5   --5   /  4 + 5

                                                                                                     0 / 9 == 0