There are a total of 10 pigs and ducks in the barn. There are 36 legs in all (each pig has four legs and each duck has two legs). Use substitution to solve the linear system of equations and determine how many pigs, x and ducks, y there are. Express the solution as an ordered pair (x, y).​

Agroup of student volunteers participates in a study designed to assess several behavioral interventions for improving output in a repetitive task. prior to the beginning of the study, all volunteers unknowingly observed, and their output is measured. at the beginning of the study, prior to any intervention, the volunteers perform the same task under the observation of a study administrator, and their overall output increases. which of the following terms describes this phenomenon? a. simpson's paradox b. hawthorne effect are d. novelty effect d. pygmalion effect e. observer-expectancy effect