Answer:
4.6 hours
Explanation:
we first need to calculate the total distance he covered and total time taken whole for the journey.
Distance= speed X time
time = Distance/speed
let the total distance be X. he covers 2/5 if the journey first.
2/5 = 0.4
Time = 0.4x/45 hours
the remaining journey is 3/5x
he covers 1/3 X 3/5= 0.2x
time taken = 0.2/90 X hours
the remaining distance = 100× 1.2 = 120km
we add 0.4x + 0.2x to get the fraction he had covered
0.6x.
the remaining distance was X - 0.6x = 0.4 X
thus 120 km represents 0.4x of the journey
we calculate now the value of X
0.4x = 120
X = 300km
Total time taken = 0.4x/45 + 0.2/90 + 1.2 hours
replace X to get time
2.7 hours + 0.7 hours + 1.2 hours
= 4.6 hours