The sum of infinite GP is given by
$${S}_{\infty}=\cfrac{a}{1-r}$$where $$a=$$ first term and $$r=$$ common ratio
And $$\left| r \right| <1$$ if $${S}_{\infty}$$ is to exist
Find the common ratio
$$r=\cfrac{{u}_{n}+1}{{u}_{n}}$$
$$r=\cfrac{6}{8}=\cfrac{3}{4}$$
$$\left| r \right| <1$$ $$\therefore$$ $${S}_{\infty}$$ exists
$${S}_{\infty}=\cfrac{8}{1-\cfrac{3}{4}}=8\cfrac{4}{1}=32$$