I have done this problem for you. If the first group consists of X people and the second group consists of Y people, there are three groups of 20-x-y people. There is an equation: 8x+6y+5(20-x-y)= 120. Solve the relationship between x and y .. Because there are at least two people in each group, starting from x=2, there are corresponding y values, so the three groups of people come out as soon as they are reduced. Add 1 to the value of x in turn to find out the number of people in each group. Finally, when there are less than two people in a group, it will stop. Check the number of inspection groups again at this time.

In the scheme design, we should pay attention to find out what X is, whether it is an inequality or an equation, express all the quantities we need to know with unknowns, and clarify our thinking.

The full text is played by mobile phone, hope to adopt it.