Answer:
10
Explanation:
Since the triangles are similar then the ratios of corresponding sides are equal, that is
scale factor =
=
=
![(1)/(2)](https://img.qammunity.org/2021/formulas/physics/middle-school/ukxexrkoplrwscaxd96qbbkphc5fo6w2ur.png)
That is the sides of Δ PQR are half those of Δ XYZ, thus
The perimeter of Δ PQR is half Δ XYZ, that is
perimeter of Δ PQR =
× 20 = 10