I think the equation V1/T1 = V 2/T2 applies to the question
but I can't work out how to use it properly

I need to calculate the volume of both solid and gas carbon dioxide and compare them to work out how much the volume changes through sublimination.

Thank you

I think that equation is used for the gas phase. It won't work for solid CO2. You need to Know the number of moles of CO2 present? You use the moles to work out the rest.You might also need the mass and density of solid CO2 to get the volume of the solid CO2. I wish I could see the question