Boyle shows the relationship between the pressure of gas and its volume at a constant temperature.
if volume of the gas increases, its pressure decreases, and vice versa. mathematically, if the volume of the gas is V₁ and its pressure is P₁. assuming that its volume has been increased to V₂, according to Boyle's law its pressure will decrease if the new pressure is P₂.
P₁ V₁ =P₂V₂
P₁ = 0.860 atm
V₁ = 11.2 L
P₂ = ?
V₂= 15 L
0.860 atm x 11.2 L = P₂ x 15 L
P₂ = 0.642 atm