Given:
In ΔPQR, Perimeter is 55 units.
The length of PQ = 2x+4
The length of PR = x+3
The length of Q+R = x
To find the length of QR, that is x:
Perimeter of the triangle formula is,
[tex]P=\text{ Sum of the length of thre}e\text{ sides}[/tex]So, we have
[tex]\begin{gathered} 2x+4+x+3+x=55 \\ 4x+7=55_{} \\ 4x=48 \\ x=12 \end{gathered}[/tex]Then, the length of QR is, 12 units.