Hello!
The answer is: Charle's Law.
Why?
The law that states that the volume and absolute temperature of a fixed quantity of gas (ideal gas) are proportional under constant pressure is the Charle's Law, also known as the law of volumes.
The law describes how a gas kept under constant pressure tends to expand when the temperature increases and it's described by the following equation:
![(V)/(T)=k](https://img.qammunity.org/2020/formulas/chemistry/middle-school/6lvs4mtyusdpafuvaia46uomukdnbrxq63.png)
Where,
![V=Volume\\T=Temperature\\k=constant](https://img.qammunity.org/2020/formulas/chemistry/middle-school/1e6d2igbn1dmoycxi1scf8sqcqkvrbdvo2.png)
Also, to describe the relationship between two differents volumes at different temperatures, we have:
![(V_(i))/(T_(i))=(V_(f))/(T_(f))](https://img.qammunity.org/2020/formulas/chemistry/middle-school/cg9y04y0sucwjooud9r1jo8bn5swq5hxhb.png)
Where,
![V_(i)=InitialVolume\\T_(i)=InitialTemperature\\V_(f)=FinalVolume\\T_(f)=FinalTemperature](https://img.qammunity.org/2020/formulas/chemistry/middle-school/b2q6gwzxumuei7fj3omeeou8h53wdbgtmy.png)
Have a nice day!