Help inverse functions

Could somebody me with this radical simplification?

The bottom of ignacio's desktop is 74.5cm from the floor. ignacios sits in his adjustable chair, and the tops of his legs are 49.3cm from the floor. each clockwise rotation of the knob on the chair raises ignacio's legs by 4.8cm. write an inequality to determine the number of clockwise rotations, r, ignacio could make with the knob without his legs touching the desk.

The amount of data left on the cell phone six gb for 81.5 gb of data is used how much data is available at the beginning of the cycle