A physical quantity obtained from the ratio of the coefficient of thermal conductivity to the universal gravitational constant has a dimensional formula $M^{2a}{L}^{4b}{T}^{2c}{K}^d$ then the value of $\frac{a+b}{c+b}-d$ is : 

Dimensional formula of thermal conductivity
$\left[\mathrm{K}\right]=\left[M^1{L}^1{T}^{-3}{K}^{-1}\right].$

Dimensional formula of universal gravitational constant, $\left[G\right]=\left[m^{-1}{L}^3{T}^2\right]$

$\text{ Now, }\frac{\left[K\right]}{\left[G\right]}=\left[M^2{L}^{-2}{T}^{-1}{K}^{-1}\right]$

compare above equation with

 $$\begin{gathered} \text{ This will give us, }\mathrm{a}=1,\mathrm{b}=-\frac{1}{2},c=-\frac{1}{2}\text{ and }=-1 \\ \text{ This will give us, }a=1,b=-\frac{1}{2},c=-\frac{1}{2}\text{ and }d=-1 \\ Now, \\ \frac{a+b}{c+b}-d=\frac{1-\frac{1}{2}}{-\frac{1}{2}-\frac{1}{2}}-(-1)\text{ or }\frac{a+b}{c+b}-d \\ =\frac{1}{2} \end{gathered}$$