Answer:
600 g of flour.
Explanation:
If Deon needs 50 g of sugar to make 15 biscuits, and she is going to make 60 biscuits, then she will need 200 g of sugar, since 60/15 is 4.
If the amount of flour she needs is equal to the amount of sugar multiplied by three, or 3x, if x is the amount of sugar, then she will need 200 x 3 g of flour.
Therefore, she will need 600 g of flour.