40 students are going on a field trip to the aquarium. every student needs to be in a group, and all groups must have the same number of students. if there is 1 group, there will be students in the group. if there are groups, there will be 20 students in each group. if there are 4 groups, there will be students in each group.

Luke started a weight-loss program. the first week, he lost x pounds. the second week, he lost pounds less than times the pounds he lost the first week. the third week, he lost 1 pound more than of the pounds he lost the first week. liam started a weight-loss program when luke did. the first week, he lost 1 pound less than times the pounds luke lost the first week. the second week, he lost 4 pounds less than times the pounds luke lost the first week. the third week, he lost pound more than times the pounds luke lost the first week.