Answer: 22 houses.
Step-by-step explanation:
1. You can calculate the number of houses sold last month as following:
[tex]70houses*\frac{2}{5}=28houses[/tex]
2. You can calculate the number of the remaining houses sold this month as following:
[tex]28houses*\frac{5}{7}=20houses[/tex]
3. Then, the number of houses are left to be sold is:
[tex]70houses-28houses-20houses=22houses[/tex]
