Slope of line making an angle of -45° with the positive x-axis = tan(−45 ) = −tan(45 ) = −1 Equation of line passing through (x1,y1) and making slope m is (y−y1)=m(x−x1) Equation of line passing through (2,-3) and slope = -1 ⇒ (y+3)=−1(x−2) ⇒ y+3=−x+2 ⇒ x+y=2−3=−1