Start with the grammar G6, repeated here: G6: ::= + | ::= * | ::= ( )

Question:

Start with the grammar G6, repeated here:
G6: ::= + |
::= * |
::= () | a | b | c
Modify it in the following ways:
a. Add subtraction and division operators (- and /) with the customary precedence and associatively.
b. Then add left-associative operator % between + and * in precedence.
c. Then add right-associative operator = at lower precedence than any of the other operators.