1. The problem statement, all variables and given/known data On a warm day, a student uses a tire gauge to test the air pressure of her tires. While listening to the weather report on the way to the garage, she finds that the barometric pressure is 780mmHg. If the gauge reads a pressure of 35psi, what is the actual pressure inside the tires in psi? 2. Relevant equations I don't know which equation I should be using. Is it a trick question because the tyre pressure doesn't change or is it Pgauage= Pabsolute - Pambient 3. The attempt at a solution if it is then I'm assuming that absolute pressure is the same as actual pressure. Then Pgauage= 35psi Pambient= 780mmHg= 15.0868psi and I have to find Pa which would be Pabsolute=35 + 15.0868 = 50.868 psi Like I said I have no idea....thanks!