Let boys and girls be x, y and z respectively, and two equations can be obtained according to the topic:

x+y+z=72

4x+3y+z/3=72

After sorting,11x+8y =144 can be obtained. At this time, it is necessary to consider the attributes of X, Y and Z. Because it is the number of people, X, Y and Z need to be positive integers, so after comparison, x=8, y=7 and z=57.