Centroid of a Triangle

Find the coordinates of centroid of the triangle with vertices following:

$(1,-1), (0,6)$ and $(-3,0)$

Find the coordinates of centroid of the triangle with vertices following:
$(6,2), (0,0)$and $(4,-7)$

Find the coordinates of centroid of the triangle with vertices following:

$(-1,3), (6,-3)$ and $(-3,6)$

 Find the centroid of the triangle formed by the line $2\mathrm{x}+3\mathrm{y}-6=0$ with the coordinate axes.