To solve this equation, you will need to set up a proportion where you set two fractions equal to each other.
Let x = the unknown amount of milk
You would then crossmultiply and solve for x.
8x = 400(6)
8x = 2400
x = 2400/8
x = 300
You will need 300 mL of milk to make 6 pancakes if you previously needed 400 mL to make 8 pancakes.