Problem 4.7. Denis threw darts at four identical dartboards: he threw exactly three darts at each board, where they landed is shown in the figure. On the first board, he scored 30 points, on the second - 38 points, on the third - 41 points. How many points did he score on the fourth board? (For hitting each specific zone - ring or central field - a certain number of points is awarded.)
![](https://cdn.mathpix.com/cropped/2024_05_06_ff369b3e8ca7495bdf12g-06.jpg?height=260&width=1136&top_left_y=960&top_left_x=156)
Answer: 34.

Solution. "Add" the first two dart fields: we get 2 hits in the central field, 2 hits in the inner ring, 2 hits in the outer ring. Thus, the sum of points on the first and second fields is twice the number of points obtained for the fourth field.

From this, it is not difficult to get the answer

$$
(30+38): 2=34
$$