I think Gayathri Ram is correct.
We don't know the house no. Then How the sentence " The sum of the ages equals the no. of our house"
will help us to arrive the Answer. It doesn't mean that the sum of the ages equals the House No. twice. As per Maheswari Mam's reply, the house no. is 13. Why don't the House No. is 11 or any other.