It looks like you've written out several algebraic expressions. Let me help you simplify them one by one.

1) $a + 4$

This expression is already in its simplest form.

2) $2a^2 + 7a - 4 + a - 4$

Combine like terms: $2a^2 + (7a + a) - (4 + 4) = 2a^2 + 8a - 8$

3) $b - 1$

This is also in its simplest form.

4) $b^2 + 7b + 6 + 2b - 4$

Combine like terms: $b^2 + (7b + 2b) + (6 - 4) = b^2 + 9b + 2$

5) $x + 6$

This expression is already simplified.

6) $4x^2 - 24x - x + 4$

Combine like terms: $4x^2 - (24x + x) + 4 = 4x^2 - 25x + 4$

7) $n + 5$

This expression is already simplified.

8) $6n^2 - 18n - n + 4$

Combine like terms: $6n^2 - (18n + n) + 4 = 6n^2 - 19n + 4$

9) $v + 6$

This is in its simplest form.

10) $3v^2 - 18v + v + 4$

Combine like terms: $3v^2 - (18v - v) + 4 = 3v^2 - 17v + 4$

11) $2p + 6$

This expression is already simplified.

12) $p^2 - 2p - 15 - 3$

Combine like terms: \