To make the chocolate shake, dona added 40 ml of chocolate syrup,
200 ml of milk, and 400 ml of water. how much milk, in liters, would be
required if she uses 450 ml of water?

0.225 L of milk, would be required if she uses 450 m L of water.

Step-by-step explanation:

Here, to make the shake, ingredients used by Dina are:

40 m L of chocolate syrup,

200 m L of milk, and 400 m L of water.

So, here Amount of water used = 2 x ( Amount of Milk used)    (1)

Now,again the amount of water used by Dona = 450 m L

Let us assume the milk used by her  = k m L

⇒ 450 m L = 2 x ( k m L)     ( from (1))

or, 450 = 2  k

⇒  k    = 450/2  = 225

⇒   k   = 225 m L

Also, 1 m L = 0.001 L

So, 225 m L = 225 x  0.001  = 0.225 L

⇒   k   = 0.225  L

Hence, 0.225 L of milk, would be required if she uses 450 m L of water.