1. The problem asks to find the value of the composition of functions $(c \circ d)(4)$, where $c(x) = 2x$ and $d(x) = 6x$. 2. The composition of functions $(c \circ d)(x)$ means $c(d(x))$, which is applying $d$ first, then $c$ to the result. 3. First, calculate $d(4)$: $$d(4) = 6 \times 4 = 24$$ 4. Next, apply $c$ to the result of $d(4)$: $$c(d(4)) = c(24) = 2 \times 24 = 48$$ 5. Therefore, the value of $(c \circ d)(4)$ is $48$.