Take, for example, any recipe. In order to produce meal, you have to take ingredients in strict proportions, like, 500 grams of flour, 100 grams of sugar, etc. But what if, for example, you have only 400 grams of flour, or want to use all remaining 700 grams? In this case you have to scale quantities of all other ingredients, proportionally.
So, formally, I can describe this problem like this: we have quantities of ingredients for some mixture or recipe, and we have to recalculate these quantities if quantity of one component has changed.
To recalculate these quantities you can use the calculator below. You enter standard quantities of ingredients in the table, then you enter how one of the ingredients has changed. Results table contains recalculated quantities for all ingredients.