Match the vocabulary to the proper definition. two quantities that increase or decrease (change) by the same factor; also known as directly related

a method of paying someone based on a percentage of their sales

a small amount of money given for a service

the rate of change in a direct variation; also known as the constant of proportionality

multiplying diagonally across the equal sign in a proportion

commission
cross multiplication
directly proportional
constant of variation
gratuity (or tip)