Boyle's Law question: An ideal gas is allowed to expand from 9.00 L to 22.5 L at constant temp.

By what factor does the volume increase? ____Number??? totally lost
The pressure will increase or decrease? If the initial pressure was 113 atm, what is the final pressure?
Thank you for your help. This is like learning a foreign language.

Boyle's Law states that pressure and volume are inversely related; as the pressure increases, the volume goes down, and vice versa. In an equation, this can be represented as:
P(1) * V(1) = P(2) * V(2)
In order to calculate the factor by which the volume increases, though, one simply needs to divide the end volume by the starting volume. So, 22.5 / 9 = 2.5; the volume increases by a factor of 2.5.
Since the volume increased, Boyle's Law states that pressure must decrease.
If the starting pressure was 113 atm, then we can call that P(1). The starting volume of 9.00 L can be V(1) and the ending volume of 22.5 L V(2). Then, solve the equation for P(2), and plug in the values.
P(1) * V(1) = P(2) * V(2) --> [P(1) * V(1)] / V(2) = P(2)
P(2) = (113 atm * 9.00 L) / 22.5 L = 45.2 atm