Answer:
Perimeter of triangle PQR = 181.5 mm
Explanation:
Midsegment theorem states that,
"Midsegment connecting the midpoints of the two sides of a triangle is parallel and half of the length of the third side"
From the figure attached,
PQ =

=

= 41.5 mm
PR =

=

= 55 mm
QR =

=

= 85 mm
Perimeter of triangle PQR = PQ + QR + PR
= 41.5 + 55 + 85
= 181.5 mm