If a = 4/7 what's the multiplicative inverse of a

We just started the introduction into circles and i have no idea how to do this.

Acar loses a quarter of its value every year. it is originally worth $35,000. to the nearest dollar,how much will the car be worth in 8 years?

‼️‼️‼️‼️‼️the pressure exerted on the walls of a container by a gas enclosed within it is directly proportional to the temperature of the gas. if the pressure is 6 pounds per square inch when the temperature is 440 f, find the pressure exerted when the temperature of the gas is 380°f. (show work)