Les wants to make 20 scones, but the recipe is for 8. The recipe requires 350g flour, 90g butter, 100g sultanas, and 170ml milk. How much of each ingredient is needed for 20 scones?

The recipe is for 8 scones, and Les wants to make 20 scones.

$$\text{Scaling factor} = \frac{\text{Desired number of scones}}{\text{Original number of scones}} = \frac{20}{8} = 2.5$$

$$\text{Milk} = 170\, \text{ml} \times 2.5 = 425\, \text{ml}$$

Les needs the following amounts of each ingredient:

• Flour: $\boxed{\text{875 g}}$
• Butter: $\boxed{\text{225 g}}$
• Sultanas: $\boxed{\text{250 g}}$
• Milk: $\boxed{\text{425 ml}}$