Cody and Brandon started on a 45-km cycling trip at the same time. They cycled at the same speed for first 10 km. For the remaining 35 km, Cody cycled faster than Brandon. He arrived at the finishing point 30 minutes before Brandon who was 10 km behind him. Brandon did not change his speed throughout and completed it at 07 25.

1. At what time did the trip begin? Give the answer in 12-hour format.
2. What was Cody's average speed for the remaining 35 km of the trip in km/h?

(a)
60 min = 1 h
30 min =³⁰₆₀ h = ¹₂ 

Brandon's average speed
= 10 ÷ ¹₂
= 20 km/h

Time that Brandon took for the trip
= 45 ÷ 20
= 2⁵₂₀ h
= 2¹₄ h
= 2 h 15 min

2 h 15 min before 07 25 is 05 10.

(b)
To find the time that Cody took for the remaining 35 km of the trip, we need to use the time that Brandon took subtract that of the time taken for first 10 km and the time that Cody was faster than Brandon.

Time that Cody took for the remaining 35 km of the trip
= 2¹₄ - ¹₂ - ¹₂
= 1¹₄ h

Cody's average speed
= 35 ÷ 1¹₄
= 28 km/h

Answer(s): (a) 05 10; (b) 28 km/h