For this case we have the following expression:
[tex]a + b-c-d[/tex]
We must evaluate the expression when:
[tex]a = 27\\b = 26\\c = 27\\d = 23[/tex]
Substituting the values we have:
[tex]a + b-c-d = 27 + 26-27-23[/tex]
Equal signs are added and the same signs are placed.
[tex]a + b-c-d = + 53-50[/tex]
Different signs are subtracted and the sign of the major is placed:
[tex]a + b-c-d = 53[/tex]
Finally we have to:
[tex]a + b-c-d = 53[/tex]
Answer:[tex]a + b-c-d = 53[/tex]