If $$(2x + 3y + 4)(2x + 3y - 5)$$ is equivalent to $$(ax^2 + by^2 + 2hxy + 2gx + 2fy + c)$$, then what is the value of $$\left\{\frac{g + f - c}{abh}\right\}$$

Given that  $$(2x + 3y + 4)(2x + 3y - 5)$$

$$\Rightarrow2x(2x+3y-5) +3y(2x+3y-5) +4(2x+3y-5)$$ 

$$\Rightarrow 4x^2 +6xy -10x +6xy +3y^2 -15y +8x +12y -20 $$

$$\Rightarrow 4x^2 +9y^2 +12xy -2x -3y -20 $$

Compairs $$ax^2+by^2 +2hxy +2gx +2fy +c $$

then a= 4 , b= 9 , 2h= 12 , h= 6 , g= -1, f =$$\dfrac -{3}{2}$$ , c= -20 

therefore 

$$\left\{\frac{g + f - c}{abh}\right\}$$

put the value 

$$\Rightarrow  \dfrac{-1-\dfrac{3}{2}+20}{4\times9\times6}$$

$$\Rightarrow \dfrac{35}{432}$$ Ans