MATHE HELP(INVERSE VARIATION) PLEASE HELP ASAP?

Joe is trying to soup up his dragster. He knows that the time needed for the car to go from 0 to 100 miles per hour varies inversely with the car's horsepower. At 200 horsepower, the car can go from 0 to 100 mph in 10 seconds. How long should the car take if he can increase the horsepower to 250 hp?

The volume (V) of a gas varies inversely as the pressure (P) upon it. The volume of a gas is 200 cubic centimeters under a pressure of 32 kg per square centimeter. What will be its volume under a pressure of 20 kg per square centimeter?

Complete the equation of variation where y varies inversely as x and y = 80 when x = 0.7.

Rosa has designed a pulley system for a school science project. She has determined that as the coefficient of friction increases, the efficiency of the pulley decreases. With a coefficient of friction of 0.2, the efficiency of the pulley is 60%. What would you expect the efficiency to be if the coefficient of friction increased to 0.3?

Complete the equation of variation where y varies inversely as x and y = 0.125 when x = 8.

Rosa has designed a pulley system for a school science project. She has determined that as the coefficient of friction increases, the efficiency of the pulley decreases. With a coefficient of friction of 0.2, the efficiency of the pulley is 75%. What would you expect the efficiency to be if the coefficient of friction increased to 0.3?

John is trying to drain a swimming pool. He has two pumps, but he can only use one at a time. He knows that the time a pump takes to drain the pool varies inversely with the power in watts of the pump. His old pump is a 40 watt pump, and it can drain the pool in 5 hours. How long would the job take if he uses his new 100 watt pump?