Please help, its due soon

Old Faithful is a geyser in Yellowstone National Park that erupts according to an arithmetic sequence. The eruptions generally happen in 46 minute intervals with a constant difference of 12 minutes. Suppose that you are in the park and you know the last eruption was at 12:22 p.m. That eruption was the 4th eruption of the day. About when can you expect the geyser to erupt again? Explain.