Answer:
10
Step-by-step explanation:
Set up as a proportion:
[tex]\frac{QR}{QP}=\frac{BA}{BC}[/tex], insert given values
[tex]\frac{?}{12}=\frac{30}{36}[/tex], cross multiple
36*?=30*12
36*?=360, divide both sides by 36 to get the missing side (?) by itself
?=10
