Cross Sum

[gabriele]

each group of 3 consecutive yellow cells (horizontal and vertical) has the same sum (sum of the 3 digits)

[gabriele]

hint to solve the cross
consider columns 3 & 7
the sum of cells outside the cross MUST BE ODD
in column 3 the odd sums are 13 and 19
in column 7 are 19 and 21
therefore the only possible sum is 19
and the sum of each cross is (45-19)/2=13