Recall the ideal gas law:
P V = n R T
where
P = pressure
V = volume
n = number of gas molecules
R = ideal gas constant
T = temperature
If both n and T are fixed, then n R T is a constant quantity, so for two pressure-volume pairs (P₁, V₁) and (P₂, V₂), you have
P₁ V₁ = P₂ V₂
(since both are equal to n R T )
Solve for V₂ :
V₂ = P₁ V₁ / P₂ = (104.66 kPa) (525 mL) / (25 kPa) = 2197.86 mL