To find \( f(x) - g(x) \), we first need to write down the functions explicitly:
- \( f(x) = x^2 + 12x + 20 \)
- \( g(x) = x + 10 \)
Now, we will subtract \( g(x) \) from \( f(x) \):
\[ f(x) - g(x) = (x^2 + 12x + 20) - (x + 10) \]
Next, we will distribute the subtraction across the terms in \( g(x) \):
\[ f(x) - g(x) = x^2 + 12x + 20 - x - 10 \]
Now, we will combine like terms:
- For the \( x \) terms: \( 12x - x = 11x \)
- For the constant terms: \( 20 - 10 = 10 \)
Thus, we have:
\[ f(x) - g(x) = x^2 + 11x + 10 \]
The final result, expressing \( f(x) - g(x) \) as a polynomial in simplest form, is:
\[ \boxed{x^2 + 11x + 10} \]