Boyle's law states that the volume (v) of a gas and its pressure (p) are inversely proportional.
If we multiply both sides by P, we get: PV = Constant
This relationship is true because if the pressure increases, the volume decreases, but the product P x V is always equal to the same constant. For two different sets of condtions, we can say that
P1V1 = Constant = P2V2 or P1V1 = P2V2.
Where P1 and V1 are the initial pressure and volume of the gas, and P2 and V2 are the final volume and pressure.
Your problem is given: 2.50 L of a sample gas
1.15 atm of Pressure
Find: the volume of the atomosheric pressure
I am not sure if you have a third variable, but if not then you would use the formula of:
V(volume) = Constant divided by P (pressure)
Therefore, 2.50 L is your constant and 1.15 atm is the pressure.
2.50 L / 1.15 atm = 2.173913043 The average answer would be 2.17 using three significant figures for your answer.