posted by Jane .
Jess is running around a circular track, one lap every 40 seconds. Mackenzie is also running at a constant speed around the same track, but in the opposite direction. They meet every 15 seconds. How many seconds does it take Mackenzie to do one lap?
d1 = (15s/40s) * 1Lap = 15/40=3/8 Lap =
d1 + d2 = i Lap.
3/8 + d2 = 1
d2=1 - 3/8 = 5/8 Lap in 15s.=Mackenzie'
T = 15s/(5/8)Lap = 15 * 8/5 = 24 s/Lap.
= Mackenzie' speed.