Step-by-step explanation: To solve for the proportionality between x = 21 and y = 6, we must identify the constant of proportionality in that x = ky. We can construct our equation accordingly:
[tex]21 = 6k[/tex]
When we divide by the coefficient (6), we find:
[tex]\dfrac{21}{6} = 3.5[/tex]
[tex]\dfrac{6}{6} = 1, \ or \ k[/tex]
Finally, we find that 3.5 = k. Therefore, the constant of proportionality amounts to 3.5.
