Here is a model of a closed economy: C(Yd)=80+0.8Yd I(r0)=100 G=100 (a) consider two tax systems (and a balanced budget policy): a lump sum tax (T=G) and a proportional tax (G=T(Y)=tY. will the equilibrum level of output be different under the two tax systems? (b) what will be the level of t?