1) an ice cream factory makes 320 quarts of ice cream in 10 hours.
how many quarts could be made in 12 hours? what was that rate per day?

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.