A) the marginal propensity to save is the number associated with y which is 0.8
B) the marginal propensity to save is 1-0.8 = 0.2
C) replace y with the 400 and solve: c = 40 + 0.8(400) = $360
D) Average propensity to consume = 360/400 = 0.9
E) 400-360 = $40
F) 40/400 = 0.1