Two finite sets have m and n(m, n) elements. The number of subsets of the first set is 112 more than that of the second set. The value of mn is

According to the question,2m−2n=112⇒ 2n2m−n−1=24×7Compering exponents on both side, we get2n=24 and 2m−n−1=7Now, 2n=24⇒ n=4And 2m−n=8⇒    2m−n=23⇒    m−n=3⇒    m−4=3∴    m=7