Direction ratio of the given line are −2,d and -4 ⇒−2+ad−4b=0.......(i) ‌ and ‌2b+ad−20=0.......(ii) subtracting equation (i) and (ii) ‌6b−18=0 ‌b=3 also, line passes through the point (0,‌
−1
2
,0) ‌⇒‌
0−1
−2
=‌
−
1
2
+4
d
=‌
0−c
−4
‌⇒d=7,c=2 From equation (i) ‌−2+7a−12=0 ‌⇒a=2 ‌a+b+c+d=14