I think I might have solved this.

Work = Rate x Time

1 job = 8 Rate (because 8 people) x 42 days

Solving for the rate: R = 1/336

Therefore, the new equation taking into consideration that one worker is now work half days:

1 job = 7.5 rate x Time

1 job = 7.5 (1/336) x Time

Solving for time, it is 44.8 days. Is this the correct way to solve it?

Thanks in advance!