At 225.0 °c a gas has a volume of 400.0 ml. what is the volume of this gas at 127.0°c?

T₁ = 225.0 + 273.15 => 498.15 k

t₂ = 127.0 + 273.15 => 400.15 k

P₁v₁ / t₁ =P₂v₂ / t₂

1 x 400.0 /  498.15 = 1 x V₂ / 400.15

498.15 x V₂ = 400.15 x 400

498.15 V₂ =160060

V₂ = 160060 / 498.15

V₂ = 321.3 mL

hope this helps!