Answer:
84%
Step-by-step explanation:
The probability of Thomas bumping into her at school is 80%, so the probability of not bumping into her is 100% - 80% = 20%.
If he doesn't bump into her (20% chance), he will call her, and the probability of asking her in this case is 60%, so the final probability of asking her in this case is:
If he bumps into her (80% chance), the probability of asking her is 90%, so the final probability of asking her in this case is:
To find the probability of Thomas inviting Madeline to the party, we just have to sum the probabilities we found above: