Bihar Police Constable Model Paper 6

GIVEN:
Two cyclists A and B are 90 km apart. If they start moving in the same direction they will meet after 6 hours. If they start moving towards each other, they will meet after 3 hours.
CONCEPT:
Relative speed concept.
FORMULA USED:
Speed = Distance/Time
CALCULATION:
Suppose the speed of cyclists A and B are x and y km/hr respectively.
So,
90/(x - y) = 6
⇒ (x - y) = 15 ----(1)
And
90/(x + y) = 3
⇒ (x + y) = 30 ----(2)
Solving equations 1 and 2:
⇒ x = 22.5 and y = 7.5
Hence,
Speed of slower cyclist = 7.5 km/hr