yung ginamit ko po jan na method sir is yung naderive ko po based on some observations in solving parallel problems..

MD = (144/143)(MM+(MH/12))
MA = MH+(MD/12)

where,
MD = minutes of departure
MA = minutes of arrival
MH = minutes of the hour hand = 5*(kung anong oras) (e.g 10o'clock, MH=10*5=50)
MM = minutes of the minute hand

may two cases po sya:

case 1: if yung hour hand nauuna sa minute hand
case 2: if yung minute hand nauuna sa hour hand
*with respect po sa 12 o'clock mark clockwise direction

for case 1, MM = 5*(MH + greater hour)
for case 2, MM = 5*(MH + lesser hour)

yung lesser & greater hour is yung "after he returned ___ to ___ hours".

di ko po alam if may mali sa derivation ko..pero tama nman po so far sa mga sinolve kong problems :)