SSC CHSL 9 Jan 2017 Shift 1 Paper

Slope of line making an angle of -45° with the positive x-axis = tan(−45 ) = −tan(45 ) = −1
Equation of line passing through $\left({\mathit{x}}_1,{\mathit{y}}_1\right)$ and making slope m is $\left(\mathit{y}-{\mathit{y}}_1\right)=\mathit{m}\left(\mathit{x}-{\mathit{x}}_1\right)$
Equation of line passing through (2,-3) and slope = -1
⇒ $\left(\mathit{y}+3\right)=-1\left(\mathit{x}-2\right)$
⇒ $\mathit{y}+3=-\mathit{x}+2$
⇒ $\mathit{x}+\mathit{y}=2-3=-1$