24. The positive integers $m$ and $n$ are such that $10 \times 2^{m}=2^{n}+2^{n+2}$. What is the difference between $m$ and $n$ ?
A 1
B 2
C 3
D 4
E 5
24. A We are given that $10 \times 2^{m}=2^{n}+2^{n+2}$. Therefore $5 \times 2 \times 2^{m}=2^{n}\left(1+2^{2}\right)$.
Hence $5 \times 2^{m+1}=2^{n} \times 5$. So $m+1=n$. Therefore the difference between $m$ and $n$ is 1 .