Match the vocabulary terms to the correct definitions. 1. a speed or rate of change where the denominator (or second quantity measured) in the ratio is 1 constant of proportionality 2. describes variation between proportional relationships rate of change 3. the ratio of vertical change to horizontal change unit rate 4. a ratio describing vertical change to horizontal change of a linear relationship on a coordinate grid slope 5. a number, k, that represents the unit rate used in a direct variation equation y = kx for comparing proportional relationships between two variables x and y found by using division direct variation