Question

So far you have mostly worked with equations. There are special types of equations, called functions, that have exactly one output for every possible input into the equation. An example of this in the real world is the amount of money you are charged at a store: the input is the item you are purchasing, and the output is the money you are charged. Individual items have one price, so this is an example of a function. Can you think of any other examples of functions? Why might this type of equation be useful?

Answer 1

5=_+3      fill in the space, I think this is a good explanation

Answer 2

When you are baking/cooking with a recipe, the amount of specific ingredients you use determines how much of the final dish you end up with. For example, if a cookie recipe calls for 2 eggs, 1 cup of sugar etc., then doubling the recipe (4 eggs and 2 cups of sugar) would give you twice as many cookies

That's all I can come up with :)