The distance between Town C and Town D was 186 km. At 05 00, Usha left Town C and cycled towards Town D. Zara left Town C and cycled towards Town D at 05 30. Zara's cycling speed was 2 km/h faster than Usha. At 10 00, Zara caught up with Usha. When Zara was 30 km from Town D, she stopped to wait for Usha. How far was Usha from Zara when she stopped to wait for him?
Duration in which Zara cycled for before she caught up with Usha
= from 05 30 to 10 00
= 4 h 30 min
= 4 ³⁰₆₀ h
= 4 ¹₂ h

Distance that Zara cycled more than Usha
= 4¹₂ x 2
= ⁹₂ x 2
= 5 km

Usha's cycling speed
= 5 x 2
= 10 km/h

Zara's cycling speed
= 10 + 2
= 12 km/h

Distance that Zara cycled before she stopped to wait for Usha
= 186 - 30
= 156 km

Duration that Zara cycled for after she caught up with Usha and when she stopped to wait for Usha
= (156 ÷ 12) - 4¹₂
= 13 - 4¹₂
= 8¹₂ h

Distance Usha was from Zara when she stopped to wait
= 2 x 8¹₂
= 17 km

Answer(s): 17 km