The equation 4(x+3) - 2 = kx + b is true for all values of x. What is the value of k + b?

If the equation holds for all values of $x$, the two sides must be identical expressions. Expand the left side: $4(x + 3) - 2 = 4x + 12 - 2 = 4x + 10$. Matching with $kx + b$ gives $k = 4$ and $b = 10$, so $k + b = 14$. A common wrong answer is 10, which is only $b$, or 4, which is only $k$. Another is 16, from forgetting to subtract the 2 and getting $b = 12$. Always read what the question asks for: the sum, not either value alone.