Vertical Stretch by a factor of 2.5
1) Considering that we have a parent function f(x)= |x| and its transformed one: g(x) = 2.5|x| we can state that there is a factor 2.5 on the parent function that makes the following transformation:
Notice that the g(x) function has been Vertically Stretched by a 2.5 factor
2) Hence, the answer is Vertical Stretch by a factor of 2.5