A thin prism of angle 6° and refractive index for yellow light $\left({\mathrm{n}}_{\mathrm{v}}=\right)1.5$ is combined with another prism of angle 5° and ${\mathrm{n}}_{\mathrm{v}}=1.55$. The combination produces no dispersion. Then net average deviation($\mathrm{\delta }$) produced by the combination is ${\left(\frac{{\displaystyle 1}}{{\displaystyle \mathrm{x}}}\right)}^0$then $x$ is