
change the mixed numbers to improper fractions and multiply the numerators / denominators
10
= 
×
=
= 1110 
Answer: PQ = 18
Step-by-step explanation:
You would divide 21/14 to see what the size difference in the triangles is to get 1.5. 1.5x12=18
Make them the same denominator like 2/3 and 4/6 you can either simplify 4/6 t0 2/3 or do 2/2 * 2/3 and get 4/6