3. For each part below, draw the state machine of a pushdown automaton that recognizes the language specified. 20 points
a) $L_5 = \{0^{3n}1^{2n} | n \ge 0\}$
b) $L_6 = \{xy | x \in \{a, b\}^* \text{ and } y \in \{c, d\}^* \text{ and } |x| = |y|\}$
c) $L_7 = \{a^ib^jc^nd^m | 2(i + j) = n + m \text{ and } i, j, n, m \ge 0\}$