The equation 4(x+2) - 5 = kx + b is true for all values of x. What is the value of k + b?

If an equation is true for all values of $x$, both sides must be the same expression. Expand the left side: $4(x + 2) - 5 = 4x + 8 - 5 = 4x + 3$. Matching with $kx + b$ gives $k = 4$ and $b = 3$, so $k + b = 7$, choice B. Choice A (4) is $k$ alone. Choice C (3) is $b$ alone. Choice D (13) does not follow from the expansion; forgetting to subtract the 5 would give $b = 8$ and a sum of 12. Read the question: the sum of both values is needed.