My question is

Question

A party starts at two places at 8 p.m.
Clock A runs twenty minutes behind every hour and
Clock B runs fifteen minutes behind every hour.
The party will end as soon as the big hand points to
twelve on both clocks. After how many hours will the
party end?

Answer 1

A runs at 40 min/hr.

B runs at 45 min/hr.

 

What is the least common multiple (LCM) of 45 and 40?

That shall be number of minutes after 8 pm