If from the low tide to the high tide there was a break of 6h and 4m than the next tides will happen at the same rate:
8:35 + 6:04 = 14:39 = next low tide.
14:39 + 6:04 = 20:43 = next high tide.
Note that two same tides occur about 12h to 12h and 25m apart, and that is the case here:
14:39 - 2:31 = 12:08 hours apart
20:42 - 8:35 = 12:07 hours apart.
Hope it helped,
Happy homework/ study/ exam!
