This week we started Relations and Functions. This is something i think would be helpful remembering.

Relation: A comparison between two sets of elements (numbers) is a relation.

Ex. The cost of pellets is related to the weight.

To determine which is the input or the output you need to remember which one depends on which.

It does not make sense for the weight to depend on the cost therefore the sentence should be written as the cost depends on the weight. Because of this the cost is the input also known as the dependent, y and range. The weight is known as the independent, the input, and the domain.