The change in volume is by how much volume it increases. And delta p is basically the change in pressure, the difference in pressure between the inside portion of the blood vessel and the outside portion of our blood vessel. So if we change around this equation and if we bring the delta p to this side we get a linear function, we get delta v is equal to the product of c multiplied by delta p and we can easily plot this equation on the XY plot. So let's take a look at what that actually looks like. So let's plot this four arteries. So the y axis is the relative increase in volume given to us in percentage where 100% basically means the blood vessel is fully relaxed.