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5. Backus Naur Form (BNF), and Expression Trees. Consider the following BNF definition of arithmetic expressions: expression ::= term + expression | term expression | term term ::= factor * term | factor / term | factor factor ::= literal | (expression ) literal ::=0|1|2|3|4|5|6|7|8|9 a. Build the expression tree of: 8/4-9/3-3. b. Build the expression tree of: 896/3. c. Write an expression that corresponds to the following expression tree: 8 9 d. Write function evaluate () that takes an expression tree and returns its value. e. Show the trace of execution of this tree on the tree given in question (c)