If $S_{D}^{2}$ $\sum D$ = 20, N = 10, and = 4, What Is

If $S_{D}^{2}$ $\sum D$ = 20, N = 10, and = 4, what is $t_{o b t}$ when $H_{0}: \mu_{D}=0$ and $H_{a}: \mu_{D} \neq 0$ ?