Assume that disposable income increases in the economy from $3,000 to $4,000 and causes consumer expenditures to increase from $3,300 to $4,200. a. What is the economy's marginal propensity to consume? b. Are households in this economy saving or dissaving? c. What is the marginal propensity to save in the economy? d. If taxes were to increase by $400, what effect would this have on consumer expenditures