Answer:
Mr. Still finish independent reading at 9:40
Explanation:
Mr.still's class has music for 50 minutes and then independent reading for 20 mins Music start 8:30
Music starts at 8.30 and it goes for 50 minutes
8:30 + 50 minutes is 9:20
After music , independent reading for 20 mins
So we add 20 minutes with 9:20
9:20 + 20 minutes is 9:40
So , Mr. Still finish independent reading at 9:40