Answer: a) 750 ml of sugar is needed to mix with 850 mL of lemon juice.
b) 800 ml of water is needed to mix with 150 mL of sugar.
Explanation:
Given: The recipe for fresh lemonade uses 425 ml of lemon juice, 2L of water and 375 ml of sugar.
⇒ All the quantities to make the lemonade should be in proportion.
a) To find the amount of sugar is needed to mix with 850 mL of lemon juice.
let x be the amount sugar is needed to mix with 850 mL of lemon juice.
Since for 425 ml of lemon juice, 375 ml of sugar is used.
Therefore,

Hence, 750 ml of sugar is needed to mix with 850 mL of lemon juice.
b) To find the amount of water is needed to mix with 150 mL of sugar.
let y be the amount water is needed to mix with 150 mL of sugar.
Since, for 2L (2000 ml )of water , 375 mL of sugar is used .
Therefore,

hence, 800 ml of water is needed to mix with 150 mL of sugar.