Question

Find the numerical value of (c - a) + (d - b). [2 Mark]

Answer 1

$b={115}^{\circ }$ [Vertically opposite angles]
$c={140}^{\circ }$ [Vertically opposite angles]
$c=d={140}^{\circ }$ [Corresponding angles]
$a+b={180}^{\circ }$ [Co-interior angles]
$a={180}^{\circ }-b={180}^{\circ }-{115}^{\circ }={65}^{\circ }$ [1Mark]

(c - a) + (d - b) = (140° - 65°) + (140° - 115°)
= 75° + 25°
= 100° [1 Mark]