2.5 because if you move x to the other side of the equation you will get y=2.5x, and the constant of proportionality is what x is multiplied by, in this case, it's 2.5.
This equation can be used when comparing ages.
An example to illustrate this:
Assume that adding 6 to 3 times the age of Jack will give us the age of his grandfather.
When translating this into equations, assuming that the age of jack is "a" and the age of his grandfather is "b", we will find that:
b = 6 + 3a
Answer:
Negative linear relation
Step-by-step explanation:
When one variable increases (the price) while the other variable decreases (the number of hamburgers he sells) , a negative linear relationship exists.
The photo below may help you.