Complete question is:

After traveling a distance of 45 km, Aryan found that 3/8 distance of his journey was still left.

What was the length of his whole journey?

Solution:

Total distance traveled by Aryan = 45 km

Given that 3/8 distance was still left.

Let the total journey is 1

Now, 1 - 3/8 = (8 - 3)/8 = 5/8

Now, 5/8 = 45 km

So, the complete journey = 45 * 8/5 = (45 * 8)/5 = 9 * 8 = 72 km