Answer:
A proportional relationship is written as:
y = k*x
where k is the constant of proportionality.
A general word problem that represents one of these relationships can be:
If each burger costs $1.50, what would be the cost of buying x burgers?
The cost of x burgers will be x times $1.50, so if we define y as the total price, we will have the relation:
y = $1.50*x
Which is a proportional relationship where the constant of proportionality is $1,50