Table 1 below shows values of GDP, disposable income, consumption, planned investment, and planned aggregate expenditures for a hypothetical economy. Use information in the table below to derive consumption function as a function of disposable income and fill the in the missing values.

Real GDP	Disposable income	Consumption	Planned Investment	Planned Aggregate Expenditure
In billions of N$
0	`0	?	4	?
20	20	32	4	?
40	40	48	4	?
60	60	?	4	?
80	80	?	4	?
100	100	?	4	?