A’s speed = x kmph. B’s speed = y kmph. When A and B move in opposite directions they meet at C and when they move in the same direction, they meet at D. Case I, AC + CB = AB
x
2
+
y
2
=15 ⇒x+y=30.....(i) Case II, AD – BD = AB ⇒ x×
5
2
–y×
5
2
=15
5
2
(x–y)=15 ⇒x−y=
15×2
5
=6.....(ii) ∴ On adding equations (i) and (ii), x + y + x – y = 30 + 6 ⇒ 2x = 36 ⇒ x =