Using the following BNF grammar, draw parse trees or abstract syntax trees for the arithmetic expressions:

expr expr + term | term term term * factor | factor factor ( expr ) | number number number digit | digit digit 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9

(a) 3 + 4 * 5 + 6 * 7 (b) 3 * 4 + 5 * 6 + 7 (c) 3 * (4 + 5) * (6 + 7)