Let $\alpha,\beta,\gamma$ and $\delta$ be the coefficients of $x^{7},x^{5},x^{3}$ and $x$ respectively in the expansion of $(x+\sqrt{x^{3}-1})^{5}+(x-\sqrt{x^{3}-1})^{5},\,x>1.$ If $u$ and $v$ satisfy $\alpha u+\beta v=18$ and $\gamma u+\delta v=20$, then $u+v$ equals: