We know that the masses experience a 40 N force between them, which is a gravitational force due to their mass. So, if we double their distance between them, the force will decrease due to Newton's Gravitational Law.
![F=G\cdot(m_1\cdot m_2)/(d^2_(12))](https://img.qammunity.org/2023/formulas/physics/college/l0keqjq98iau9hnsw2uyko4pnyltabi9oz.png)
Let's use 2d.
![F=G\cdot(m_1\cdot m_2)/((2d)^2)=G\cdot(m_1\cdot m_2)/(4d^2)](https://img.qammunity.org/2023/formulas/physics/college/p5jlfwe0xjzg54ziirrcluoyivs4lp7hhj.png)
As you can notice, the force would be divide by 4, so let's do that.
![F=(40N)/(4)=10N](https://img.qammunity.org/2023/formulas/physics/college/csaciucm8p3v3zmckeme25z41ujf5f7p1e.png)
Therefore, if we double their distance, their force would be 10 N.