Let's denote the distance traveled on foot as "x" km.
According to the given information, the man traveled a total distance of 90 km in 9 lakh (900,000) hours. The time spent on foot and on a bicycle combined is 9 lakh hours.
The time taken to travel a certain distance is equal to the distance divided by the speed. Therefore, the time taken on foot is x/8 hours, and the time taken on the bicycle is (90 - x)/17 hours.
Since the total time spent is 9 lakh hours, we can set up the equation:
x/8 + (90 - x)/17 = 900,000
To solve this equation, we can first simplify it by multiplying all terms by 8 and 17 to eliminate the denominators:
17x + 8(90 - x) = 900,000 * 8 * 17
17x + 720 - 8x = 12,240,000
Combining like terms:
9x + 720 = 12,240,000
Subtracting 720 from both sides:
9x = 12,240,000 - 720
9x = 12,239,280
Dividing both sides by 9:
x = 1,359,920
Therefore, the man traveled a distance of approximately 1,359,920 km on foot.