text: Originally, there was enough to feed 135 people for 28 days, so 135 * 28 = 3,780 daily rations.\n\nAfter 9 days, there were 135 * 19 = 2,565 daily rations.  Now there are 36 additional people, making 135 + 36 = 171 people.  New rations are 3/4 the original size, so there are 4/3 * 2,565 = 3,420 "new rations".\n\n3,420 "new rations" / 171 people = 20 days.  Add back the original 9, and the food lasts 29 days.