Answer:
4
Step-by-step explanation:
If two variables are proportional then
[tex]y\propto x[/tex]
[tex]y=kx[/tex] ...(i)
where, k is constant of proportionality.
The given equation is
[tex]s=4c[/tex] ...(ii)
where,
s = number of cups of seltzer.
c = cups of cranberry juice.
On comparing (i) and (ii), we get
Independent variable: [tex]x=c[/tex]
Dependent variable: [tex]y=s[/tex]
Constant of proportionality: [tex]k=4[/tex]
Therefore, the constant of proportionality is 4.