She has 300 g of minced meat.
The recipe calls for 400 g of minced meat.
What fraction of the amount of minced meat the recipe calls for does she have?
(300 g)/(400 g) = 3/4 = 0.75
She has 3/4 (or 0.75) of the amount of minced meat the recipe uses, so she needs to use 3/4 of all the other amounts.
Since 3/4 = 0.75, multiply each amount in the recipe by 0.75
Minced meat: 0.75 * 400 g = 300 g
(This confirms that the fraction 3/4 = 0.75 is correct.)
Tomatoes: 0.75 * 800 g = 600 g
Stock: 0.75 * 600 ml = 450 ml
Red wine: 0.75 * 300 ml = 225 ml
