Directions
We use ratios to help us reduce recipes as well.
A marinara sauce recipe calls for 12 oz tomatoes and 4 oz onions. The ratio of tomatoes to onions is 12:4.
Let's say you only want to make half the recipe. Divide both terms in the ratio by 2. The new ratio of tomatoes to onions is 6:2.
The halved recipe calls for 6 oz tomatoes and 2 oz onions.