DSE 2012 Question 57: Open-economy macroeconomics

Consider a small open economy with fixed nominal exchange rate $E$, fixed domestic price $P$ and fixed foreign price $P^{*}$, real exchange rate $\varepsilon$. The IS equation is $Y=C+I+G+X-\dfrac{IM}{\varepsilon}$ with $C=c_{0}+c_{1}Y$, $I=d_{1}Y-d_{2}r$, $X=x_{1}Y^{*}-x_{2}\varepsilon$, $IM=m_{1}Y+m_{2}\varepsilon$. Suppose the rate of interest $r$ is exogenously given. Then a unit increase in the foreign price level, ceteris paribus, increases domestic output by