To simplify the expression \(5.4n - (-7) - 7.86n + 3.03\):
When you have a double negative, it becomes positive:
\[5.4n + 7 - 7.86n + 3.03\]
Now, combine like terms:
\[5.4n - 7.86n + 7 + 3.03\]
\[(-2.46n) + (7 + 3.03)\]
\[(-2.46n) + (10.03)\]
So, the simplified expression is \(-2.46n + 10.03\).