Ok so this is the equation and how it is rearranged

$\displaystyle I = S + ( T - G ) $

$\displaystyle =[-C_0 + ( 1 - C ) ( Y - T ) ] + T - G $

$\displaystyle Y = \frac {1}{1-C_1} ( C_0 + I + G - C_1T) $

Ok so I am confused about why this occurs $\displaystyle C_1T $

Why multiply the marginal propensity to consume by tax? Can some one explain to me how these steps are thought out , my equation rearranging is not the sharpest.