What is the constant of proportionality

Answer:
1/2
Step-by-step explanation:
1/2 x 1/2 = 1/4
3/4 x 1/2 = 3/8
1/1 x 1/2 = 1/2
5/4 x 1/2 = 5/8
(5/4 = 1 1/4)