You already had 9.0 with 84 seconds. The logic comes from clues 4 and 6. From 4 you know that 49 seconds is 6 years before 9.0. From 6 you know that 49 seconds is 6 years before 84 seconds. So 9.0 is also 84 seconds. The other clues just fall into place.

But let me know if it's correct. Sometimes it looks good but not right.