A novelty "reverse" clock runs anticlockwise at the normal speed. It was set to the correct time at 3:00 p.m., as shown. When will it next show the correct time?

After $t$ minutes the true time is 3:$00+t$ and the reverse clock shows 3:$00-t$. They match on a 12-hour dial when $2t$ is a multiple of 720, so the first time is $t=360$ min = 6 h: 9:00 p.m. (3:00 a.m. waits for 12 hours.)