You have to split it into triangles
but you have to know how to use pythagorus in 3D shapes
If Carly had more DVDs than Rob then you would subtract her amount away from the total. 42-4=38
Range
Because it has the biggest difference between the two sets (14 in set 1 and 57 in set 2) so the outlier (the value 63 in set 2) affected it the most