The sentence is “A number minus by 10 is 27”.

Let n be the number.

The word minus indicates subtraction, and the symbol is .

Thus, the numerical expression is “”

The equation is .

Apply addition property of equality: Add 10 to each side.

                    (Apply additive inverse property: )

                          (Apply additive identity property: )

                                  (Add: )

The value of the expression is 37.