How to solve these problems and specially dim(w1intersectionw2)?

(a) s 42. Th 36. Let V be the vector space of all 2 x 2 matrices over R. Consider the subspaces W = a,c,deR a C -a W ;a,b, d e R d and -a If = dim(W, n W,) and n dim( W, + W,), then the pair (m, n) is (a) (2, 3) (b) (2, 4) 43- (c) (3, 4) (d) (1, 3)