Let Kylie's container (which is 400ml) be 100%. She drank 35%. Proportion:
400ml - 100%
x ml - 35%
So Kylie drank:
x=(400*35)/100=140 ml of water
Whole Eugenia's container (350ml) is also 100% and she drank 45%.
350ml - 100%
xml - 45%
Eugenia drank:
x=(350*45)/100=157,5ml of water
Thus, Eugenia drank (157,5-140)=17,5 ml more than Kylie