Please help me to solve this, i will upvote

Given A E Rmx\" such that rank(A) = m, b E R\" and l,u,c E R", let P = {m E R\" : An: = b, 15 m S u}. a. Let 3:0 E R\". Show that so is a. basic solution to (P) if and only if A530 = b and there exist disjoint set of indices 3, N1 and N2 such that B UN1 UNg = {1, . . . ,n} and they satisfy the following properties: I B = {3(1), . . . ,B(m)} s.t. {Ajl'jes are linearly independent = 13- for all j 6 N1 I 33- =u3- for alleNg. .58 no \"C b. Suppose 3:0 is a basic solution to (P). Compute m0 in terms of b, l, u and columns of A