Answer:
Inverse variation states:
If
then the equation is in the form of :

where, k is the constant of variation.
As per the statement:
The pressure, P, of a gas varies inversely with its volume, V
By inverse variation definition;
....[1]
It is also given that a particular amount of a gas is initially at a pressure of 84 Pa at a volume of 51 L
⇒P = 84 Pa and V = 51 L
then;

⇒

If the volume(V) is expanded to 153 L then find the new pressure.
Using [1] we have;
Pa
Therefore, the new pressure be , 128 Pa