Calculate Marginal Propensity to Consume from the following data

Calculate Marginal Propensity to Consume from the following data about an economy which is in equilibrium:
National Income = 1500
Autonomous consumption expenditure = 300
Investment expenditure = 300

Y = 1500, $\overline{C}$ =300,I = 300
Y =C+l or C = Y- I =1500-300 = 1200,
b = MPC, C = $\overline{C}$ + 67, 1200 = 300+1500b
MPC or b =900/ 1500 = 0.6
MPC = 0.6