Answer:
89%
Step-by-step explanation:
If he's on time on the previous day, there's a 10% probability he'll be late, which means there's a 90% probability that he'll be on time.
If he's late on the previous day, there's a 20% probability he'll be late, which means there's a 80% probability that he'll be on time.
He's on time on Monday, so there's a 10% probability he'll be late on Tuesday and a 90% probability he'll be on time.
If he's on time on Tuesday, there's a 10% probability he'll be late on Wednesday and a 90% probability he'll be on time.
If he's late on Tuesday, there's a 20% probability he'll be late on Wednesday and a 80% probability he'll be on time.
So the probability he'll be on time on Wednesday is:
0.10 (0.80) + 0.90 (0.90) = 0.89
