Intercept plus slope for a five-point downward fit

Fit $Y=\beta_0+\beta_1x+\epsilon$ by least squares to the points $(-2,3)$, $(-1,2)$, $(0,1)$, $(1,1)$ and $(2,0.5)$. What is $\hat\beta_0+\hat\beta_1$?

$0.9$. Here $\bar x=0$ and $\bar y=1.5$. The centred cross-product is $S_{xy}=-6$ and $S_{xx}=10$, so $\hat\beta_1=-0.6$ and $\hat\beta_0=\bar y=1.5$, summing to $0.9$.