Answer
Assuming the elbow is at the origin, the coordinates for the center of mass is $(-4.92, 5.01)$
Work Step by Step
Assume the elbow is at the origin
$y_{CM}=$
$\frac{(6.6kg)(81.2m-71.7m)+(4.2kg)(0m)+(1.7kg)(0m)}{6.6kg+4.2kg+1.7kg}=5.01\%$
$x_{CM}=$
$\frac{(1.7kg)(43.1m-62.2m)+(4.2kg)(55.3m-62.2m)}{6.6kg+4.2kg+1.7kg}=-4.92\%$
If $100\%$of the height is equal to 155m,
$5.01\%=7.77m$
$-4.92\%=-7.63m$
The Coordinates for the center of mass is $(-4.92, 5.01)$
