So in math class we are doing Simplifying Algebraic Expressions or at least that is what the lesson is called but what is 7x +7. I was just wondering because it is a step in my question and im not sure if i could just add them normally or not.

Assume that there is a 11% rate of disk drive failure in a year. a. if all your computer data is stored on a hard disk drive with a copy stored on a second hard disk drive, what is the probability that during a year, you can avoid catastrophe with at least one working drive? b. if copies of all your computer data are stored on four independent hard disk drives, what is the probability that during a year, you can avoid catastrophe with at least one working drive?