given that triangle abc is transformed two times to get triangle
a"b"c"
first abc is transformed in to a'b'c' as follows:
the coordinates of a are (1,-1) and transformed into a'(-1,1)
similarly b (4,-2) became b'(-4,2) and
c(7,-2) became c'(-7,2)
i.e. (x,y) becomes (-x,-y)
this is nothing but reflection about a point here origin.
thus first transformation is reflection on the origin.
next is exactly shifting 3 units down
source: