a) Beddington and May (1982) proposed the following model to study the interactions between baleen whales and their main food source, krill: Krill (x): dx dt =rX -axy dy Whales (v): = sy with r. K, a, s, b>0. dt Assume the units for time is years, for krill is 1,000,000,000's (billions), and for whales is 1,000's (thousands) for the ecosystem modeled by these equations. b) interpret what each term in the equation means (with its units), and nondimensionalize it.