Answer with explanation:
We have to arrange different numbers ranging from 1 to 12 in each boxes such that the sum along each of the side is equal to 26.
In the first row we arrange the numbers as:
8 9 3 6
( since, 8+9+3+6=26)
In the last row we write the numbers as:
5 10 4 7
( since, 5+10+4+7=26)
In the first column we arrange numbers as:
8
1
12
5
( Since, 8+1+12+5=26 )
In the last column we arrange numbers as:
6
11
2
7
( Since, 6+11+2+7=26)