Give me an example of An economy is described as follows:

C $=400+0\mathrm{.}6($Y $$ T$)$

Ip $=200$

G $=200$

NX $=60$

T $=100$

Y$*=2,100$

a$.$ For the economy described above, find autonomous expenditure, the multiplier, short$-$run equilibrium output, and the output gap