At 6: 00 a. m. there were 68 geese in the pond. at 7: 30 a. m. there were 50 geese in
the pond. how many geese left per hour?

12 geese left per hour. At 7:30 am there were 18 less geese than there were at 6:00 am. Since there was 1.5 hours between each time, and we know that 2/3 of 1.5 hours is 1 hour, we can solve using this equation:

2/3 * 18 = 12.

or