Answer :
we will make ''X'' the result that we are searching for
and ''Y'' how much water Grayson has
So we have : X = Y + 2/5
and : Y = 2/4 - 0.4 = 1/2 - 4/10 = 1/10
So X = 1/10 + 2/5 = 5/10 = 1/2 0f a cup
and ''Y'' how much water Grayson has
So we have : X = Y + 2/5
and : Y = 2/4 - 0.4 = 1/2 - 4/10 = 1/10
So X = 1/10 + 2/5 = 5/10 = 1/2 0f a cup