Answer:
Abiola stayed at work for 8 hours and 40 minutes.
Explanation:
Abiola wasted 20 minutes waiting for her friend, so she actually left for work at 7:50 am (7:30 am + 20 minutes).
She arrived at work at 8:20 am, so she spent 30 minutes (8:20 am - 7:50 am) traveling to work.
Abiola worked from 8:20 am to 4:00 pm, which is a total of 7 hours and 40 minutes (4:00 pm - 8:20 am).
She then stayed at work for an additional 1 hour to watch African Magic, so in total, she was at work for 8 hours and 40 minutes (7 hours and 40 minutes of work + 1 hour of watching African Magic).
Therefore, Abiola stayed at work for 8 hours and 40 minutes.