Put the nine numbers 1, - 2, 3, - 4, 5, - 6, 7, - 8 and 9 into the box of the graph, so that the sum of the three numbers on each row, column and diagonal is positive

Put the nine numbers 1, - 2, 3, - 4, 5, - 6, 7, - 8 and 9 into the box of the graph, so that the sum of the three numbers on each row, column and diagonal is positive

According to the meaning of the title:

According to the following graphic rules, what should be filled in the question mark?
 

The first figure has four straight lines
The second figure has four straight lines
The third figure has eight straight lines
The fourth figure has 12 straight lines
4、4、8、12
4+4=8
4+8=12
8+12=20
The next item is 20, which means 20 lines are needed
The answer is d

According to the law of numbers in the figure, the number at the question mark is______ ．

According to the analysis, if the magic square of 6 × 6 is divided into small squares of 3 × 3, then the sum of the numbers of the four corners is the middle number,? =28-6-7-2 = 13