4. (Intersection of Subspaces, Inclusion-Ezclusion Principle for Subspaces). Let the vectors a, a as and and their linear spans Li = span(ai, az, as) and L2 = Span(b1, b2, b3) be the same as in Problem 1. (i) Represent each of L) and L2 as the solution set of a suitable homogeneous linear system. (ii) Use (i) to find a basis for the intersection L1 n L2 of L1 and L2, and the dimension of Li n L2. (ii) Use (ii) and the Inclusion-Exclusion Principle for Subspaces to find (again) the dimension of Li + I2