Let's sum these two numbers.
1 + 20 = 21 total hours.
In every 12-hour the clock format changes AM to PM or the opposite PM to AM. So we need to divide 12 with the result 21.
There are 1 times 12 number in the 21
If the result is ODD number the time format will change the opposite side. If the result is EVEN number the time format will be the same.
Answer :9pm
What is 20 hours from 1am ? = 9pm.
Add 20 hours to 1am is equal 9pm.