There are 80 new houses being built in a neighborhood. Last month, \( \frac{2}{5} \) of them were sold. This month, \( \frac{1}{4} \) of the remaining houses were sold. How many houses are left to be sold?

Last month, \( \frac{2}{5} \) of the 80 houses were sold, which amounts to \( \frac{2}{5} \times 80 = 32 \) houses. So, after last month's sales, \( 80 - 32 = 48 \) houses are left. This month, \( \frac{1}{4} \) of the remaining 48 houses were sold, which is \( \frac{1}{4} \times 48 = 12 \) houses. After this month's sales, \( 48 - 12 = 36 \) houses remain unsold. Therefore, there are 36 houses left to be sold.