Let B be an arbitrary Borel set of finite Lebesgue measure with B \subset \mathbb{R}. Show that for every \epsilon  >0 there exists a finite union of disjoint intervals A = (a_1,b_1] \cup (a_2,b_2] \cup...\cup (a_n,b_n] such that the Lebesgue measure of A \triangle B is less than \epsilon.