PLEASE HELP INVERSE VARIATION. AS SOON AS POSSIBLE PLEASE?

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?

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

If y varies inversely as x and y = 320 when x = 25, find y when x is 40.

If y varies inversely as the square of x and y = 4 when x = 5, find y when x is 2.

If y varies inversely as the square of x and y = 4 when x = 3, find y when x is 2.

The time (t) required to empty a tank varies inversely as the rate (r) of pumping. A pump can empty a tank in 90 minutes at the rate of 1200 L/min. How long will the pump take to empty the tank at 3000 L/min?

Complete the equation of variation where y varies inversely as x and y = 8 when x = 10.