So basically, you just divide the number on the bottom by the number on the top. If you get the same number for all of them, that means they are proportional.
lets take the chart for an example!
time (days): 1 // 2 // 3 //
Water(L): 225 // 450 // 675 //
225 ÷ 1 = 225.
450 ÷ 2 = 225.
675 ÷ 3 = 225.
Since they are all the same number, you can tell they're proportional!
hopefully this helped you out, but if you need anymore clarification i'm open to give some <3