Explanation:
the volume of such an object is created by multiplying the 3 side length dimensions :
length × width × height.
if you triple one of them, then you bring that factor 3 one time into the volume multiplication, and the volume also triples .
in our case that is 60×3 = 180.
FYI
if you would triple fire example all 3 dimension lengths, you would bring that factor 3 into the volume multiplication 3 times (once for every dimension).
and so the volume would increase by the factor
3×3×3 = 27.