A proportional relationship between two variables can be express as:
[tex]y=kx[/tex]
Let's write the relationships given so we can determine which is proportional.
The circumference and a diameter are related by:
[tex]C=\pi d[/tex]
The area and the length of a side of a square are related by:
[tex]A=l^2[/tex]
The perimeter and the width of a rectangle are related by the equation:
[tex]P=2l+2w[/tex]
The Fahrenheit and Celsius are related by:
[tex]F=\frac{9}{5}C+32[/tex]
By looking at all the expression we notice that onle the first one is a proportional relationship.
Therefore, the circumference and diameter of a circle
