We have a parallelogram and we have to find the length of side RQ.
Opposite sides of a parallelogram besides being parallel, they also have the same length.
Then, we can write:
![PS=QR](https://img.qammunity.org/2023/formulas/mathematics/college/2ookgvxips1e2k2qgwzdhl8q1vt2rxsj4e.png)
We can use that to find the value of x as:
![\begin{gathered} PS=QR \\ -1+4x=3x+3 \\ 4x-3x=3+1 \\ x=4 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/cuwdunwkh0gevbanp3osq27lhgn0bsentb.png)
Knowing x = 4, we can find RQ as:
![QR=3x+3=3(4)+3=12+3=15](https://img.qammunity.org/2023/formulas/mathematics/college/7skuojcje49zhsbmm813usxjag8qbkj4xl.png)
Answer: QR = 15