An automobile tire at 30°c has a pressure of 3.00 atm. temperature decreases to -5°c. assume that there is no volume change in the tire. how does the tire pressure change in response to the temperature change? what is the new pressure of the tire after the temperature change? 3.4 ⇒ 2.65 atm

This question can be explained using Gay-Lussac's law which states that:" At constant volume, the pressure of the gas is directly proportional to its temperature in kelvin degree."

This means that:
P = constant*T
For the given problem, since the temperature decreased, then we would expect a decrease in the pressure as well.

Gay-Lussac's law can be rewritten as:
P1 / T1 = P2 / T2 where:
P1 is the initial pressure = 3 atm
T1 is the initial temperature = 30 + 273 = 303 degrees kelvin
P2 is the final pressure that we want to calculate
T2 is the final temperature = -5 + 273 = 268 degrees kelvin

Substitute with the givens in the above equation to get the final pressure as follows:
P1 / T1 = P2 / T2
3 / 303 = P2 / 268
P2 = (3/303) * 268 
P2 = 2.65 atm

Idid the calculation and i get 875,000,000 which can be written as 8.75 x 10^6?