Let w be the real vector space of all 5 x 2 matrices such that the sum of the entries in each row is zero. let w2 be the real vector space of all 5 x 2 matrices

Let W be the real vector space of all 5 x 2 matrices such that the sum of the entries in each row is zero. Let W2 be the real vector space of all 5 x 2 matrices such that the sum of the entries in each column is zero. Then the dimension of the space W1 O W2 is .