Solution: If the number of people in the art group is 4X, the number of people in the model airplane group is 3X, and the number of people in the math group is (3X+3).

According to the number of math group is 65438+ 0/2 of the other two groups, there is an equation:

3X+3=(4X+3X)× 1/2

3X+3=7X/2

7X/2-3X=3

X/2=3

X=3×2

X=6

4X=4×6=24

3X=3×6= 18

3X+3=3×6+3=2 1

A: There are 24 people in the art group, model airplane group 18 and math group 2 1.