total time is 4 hours. return trip is 30 minutes longer than outgoing trip

let

t = the time of the outgoing trip

t + 0.5 since the return trip is 30 minutes longer than outgoing trip and 3o min = 30/60 hours = 0.5 hours

total time is 4 hours

t + t + 0.5 = 4

2t + 0.5 = 4

t = (4 - 0.5)/2

t = 1.75 h = 1 h 0.75*60 min = 1h 45 min

1h 45 min - 30 min = 1h 15 min the return trip

the outgoing trip took 1h 45 min the return trip took 1h 15 min.