At 09 10, Erika left Town Q and cycled towards Town R. Gillian left Town Q and cycled towards Town R at 09 40. Gillian's cycling speed was 4 km/h faster than Erika. At 13 10, Gillian caught up with Erika. Find the cycling speed of each cyclist.

1. Erika
2. Gillian

(a)
Duration that Gillian cycled from 09 40 to 13 10
= 3³⁰₆₀
= 3¹₂ h

Distance that Gillian cycled more than Erika
= 3¹₂ x 4
= 14 km

However, since Erika left 30 minutes earlier than Gillian and Gillian caught up with Erika, it means that Erika has cycled 14 km in 30 min.

1 h = 60 min 
30 min = 30 ÷ 60 = ¹₂ h

Erika's cycling speed
= 14 ÷ ¹₂
= 14 x ²₁
= 28 km/h

(b)
Gillian's cycling speed
= 28 + 4
= 32 km/h

Answer(s): (a) 28 km/h ; (b) 32 km/h