Question:
Set A has m elements and Set B has n elements. If the total number of subsets of $\mathrm{A}$ is 112 more than the total number of subsets of B, then the value of $m . n$ is..
Solution:
$2^{m}-2^{n}=112$
$\mathrm{m}=7, \mathrm{n}=4$
$\left(2^{7}-2^{4}=112\right)$
$\mathrm{m} \times \mathrm{n}=7 \times 4=28$