Answer:
k = 2
x = 2y
Step-by-step explanation:
If variables x and y vary directly, this is expressed as;
x ∝ y
x = ky
k is the proportionality constant
Let's assume the value of x and y since we are not given;
x = 20
y = 10
Substitute
20 = k(10)
10k = 20
k = 20/10
k = 2
Hence the constant of proportionality is 2
Substitute i=k = 2 into the equation x = ky
x = 2y
Hence an equation that relates x and y is x = 2y
<em>Note that the values here are assumed value, you can use the same method for any values of x and y</em>