What is the speed of an object that travels from ( -9,4,-6)  to ( 7,1,-2 )  over 3 s?

I.e $\sqrt{{\left(7 - \left(- 9\right)\right)}^{2} + {\left(1 - 4\right)}^{2} + {\left(- 2 - \left(- 6\right)\right)}^{2}} = 16.75 m$
So,speed = distance /time = $\frac{16.75}{3} = 5.57 m {s}^{-} 1$