Its on swedish but its a example i dont understand i dont understand how they got 208... I dont understand what method they use!:S
A determinant can be expanded along any row or down any column by adding together the products of each element in the row or column with their respective cofactors. In the example you show, the third column has been chosen because one of the elements is zero and that simplifies the arithmetic.
And by the way, they've made a mistake. The first bracket should be (28 + 10) and not (28 + 12).