Final answer:
To simplify the expression 31-5n+3n-19 with n equal to 15, combine like terms to get 12-2n and then substitute n with 15, resulting in a final simplified value of -18.
Step-by-step explanation:
The question asks us to simplify the expression 31−5n+3n−19 where n is equal to 15. To simplify the expression, combine like terms. The like terms here are the n terms, and the constants:
31−5n+3n−19 = (31−19) + (−5n+3n) = 12−2n
Substitute the value of n which is 15:
12−2(15) = 12−30 = −18
Therefore, the simplified expression, when n equals 15, is −18.