Consider A is a superset of B and A is uncountable.
The objective to show that B is uncountable.
Assume B is countable.
Since using the concept that every subset of countable set is
countable.
So, A is countable.
Which is contradiction, as given A is uncountable.
Therefore, B is uncountable.
\(\Rightarrow\) a superset of uncountable set is uncountable.
Hence proved.