Elimination method 2x-4y=24

Which word in the sentence below is an interrogative pronoun? who is picking us up from school? whousisfrom

To decrease an amount by 16% what single multiplier would you use

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?