(Excel) Consider the consumption function
$$
C=120+0.8 Y_{\mathrm{d}}
$$
where \(Y_{\mathrm{d}}\) is disposable income.
Write down expressions for \(C\), in terms of national income, \(Y\), when there
is
(a) no tax
(b) a lump sum tax of \(\$ 100\)
(c) a proportional tax in which the proportion is \(0.25\)
Sketch all three functions on the same diagram, over the range \(0 \leq Y \leq
800\), and briefly describe any differences or similarities between them.
Sketch the 45 degree line, \(C=Y\), on the same diagram, and hence estimate
equilibrium levels of national income in each case.