2. (20%) Consider the CFG G over the alphabet {a,b, +, x}, with initial non-terminal S, whose production rules are S + S+S | SxS | a | b Give two different parse-trees of G for the string a+bxa+b, one starting with S + S+S, and the other with S + Sx S. For the first parse-tree, present its leftmost derivation, and also another derivation