\

The sentence is “The difference between number and 12 is 54”

Let n be the number

The word difference indicates subtraction, and the symbol is

Thus, the numerical expression is “”

The equation is

 Addition property of equality: If a = b then a + c = b + c.

                      (Add 12 to both sides)

                                (Additive inverse property: )

                                      (Additive identity property: ) \ \

                                              (Add: )

The value of the expression is 66.