For this case we have the following expression:
[tex]xy = k
[/tex]
To find the constant k, what we must do is replace the following values in the given equation:
[tex]x = 7
y = 3[/tex]
Substituting values we have:
[tex]k = (7) (3)
k = 21[/tex]
Answer:
the constant of variation, k, is:
[tex]k = 21[/tex]