Elsa had 8/9 of a spool of yarn. She used 2/5 of her yarn for a project. What fraction of the spool was used for the project?

sample answer: you can determine whether each element of the domain is paired with exactly one element of the range. for example, if given a graph, you could use the vertical line test; if a vertical line intersects the graph more than once, then the relation that the graph represents is not a function.