Answer:
RS = 16
Step-by-step explanation:
If a line is parallel to a side of a triangle and intersects the other 2 sides , it divides those sides proportionally.
PR is such a line , then
[tex]\frac{QR}{RS}[/tex] = [tex]\frac{QP}{PT}[/tex] ( substitute values )
[tex]\frac{32}{RS}[/tex] = [tex]\frac{42}{21}[/tex] = 2 ( multiply both sides by RS )
32 = 2 RS ( divide both sides by 2 )
16 = RS
