A solution to an undergrad math problem

I'm forced to take a set theory....

The homework question: Find two sets A and B such that A is a member of B and A is a subset of B. I talked to my classmates and all the answers seemed a bit strange. The most common answer seemed to be A = {} and B = {{}}. That doesn't really seem right. So here is what I came up with...

A = {7}
B = {{7}, 5, 7}

A is a member of B since {7} is in B.
A is a subset of B since 7 is in B.

A = {} and B = {{}} is correct.

Clearly A is a member of B (A is the empty set, and B is a set containing the empty set).

A is also a subset of B, because the empty set is automatically a subset of any set.

Your answer is also correct.