JNU SIS 2013 Question 25: IS-LM model

The equation for the IS curve is given as $Y = \frac{c_0 + b_0 + \overline{G}}{1 - c_1(1-t)} - \frac{b_1}{1 - c_1(1-t)}\,i$ and that for the LM curve is given as $i = \frac{1}{m_2}\left(m_0 - \frac{M^S}{P} + m_1 Y\right)$ where $Y$ is income, $i$ is the rate of interest, $P$ is the price level, $M^S$ is money supply and $\overline{G}$ denotes government spending. Further, let $\dfrac{1}{1 - c_1(1-t)} = \lambda$. Then the expression for the aggregate demand function and its slope will be