Answer:
![x=10 units](https://img.qammunity.org/2019/formulas/mathematics/high-school/egs8j2uxvqrwcenpin6hhqt637aszrk8e7.png)
Explanation:
Given: The polygons ABCD and JKLM are similar.
To find: The value of x.
Solution: Since, the given polygons are similar, therefore using the similarity condition, we have
![(AD)/(JM)=(CD)/(LM)](https://img.qammunity.org/2019/formulas/mathematics/high-school/9kk2ngxuqnjmkxm2w053j51x5bxgc6n9go.png)
Substituting the given values, we get
![(12)/(40)=(3)/(x)](https://img.qammunity.org/2019/formulas/mathematics/high-school/vizxz9ttbm20b375k9zacqigptbopodzmk.png)
On cross multiplying, we get
![(3*40)/(12)=x](https://img.qammunity.org/2019/formulas/mathematics/high-school/b55ulllfrrofjuwvjrh19mu5utnei8aydx.png)
![x=10 units](https://img.qammunity.org/2019/formulas/mathematics/high-school/egs8j2uxvqrwcenpin6hhqt637aszrk8e7.png)
Therefore, the value of x is 10 units.