Answer:
See explanation
Explanation:
A parallelogram is a quadrilateral with parallel opposite sides. The main property of a parallelogram is that the opposite sides of the parallelogram are congruent.
1. Sides AB and CD are congruent, then
![4x=18\\ \\x=(18)/(4)=4.5](https://img.qammunity.org/2021/formulas/mathematics/middle-school/poizi2ln0049rcsmpegjqnduale6nna3m6.png)
2. Sides AD and BC are congruent, so
![(1)/(3)x=7\\ \\x=7\cdot 3=21](https://img.qammunity.org/2021/formulas/mathematics/middle-school/270ekhkbgrrlinsgsk8uz6jx8hkus2eu0x.png)
3. Sides AD and BC are congruent, so
![x+4=15\\ \\x+4-4=15-4\\ \\x=11](https://img.qammunity.org/2021/formulas/mathematics/middle-school/96z18jo7bxgpv1522fbcj1z1ebooc46lnt.png)