W(b) = 12b.
he has enough to build 10 birdhouses, he doesn't have for more than that, he can either build no birdhouses or build 10 birdhouses, since "b" is the independent variable and thus the domain will come from it, what values can "b" safely take? "b" can be either 0 or more than 0 but nor more than 10, because Owen doesn't have enough for more than that, 0 ≤ b ≤ 10.
let's say owen chooses to build 0 birdhouses, then W(0) = 12(0) => W(0) = 0.
let's say owen chooses to build 10 birdhouses, then W(10) = 12(10) => W(10) = 120.
so the amount of wood needed for those birdhouses, namely the range, can be either 0, if he chooses to build none, or 120 if he chooses to build 10, 0 ≤ W(b) ≤ 120.