If $2^{x}=16$, then $2^{x+3}$ equals
(A) 19
(B) 48
(C) 22
(D) 128
(E) 2048
Solution 1

Since $2^{x}=16$, then $2^{x+3}=2^{3} 2^{x}=8(16)=128$.

Solution 2

Since $2^{x}=16$ and $2^{4}=16$, then $x=4$.

Since $x=4$, then $2^{x+3}=2^{7}=128$.

ANSWER: (D)