Aline parallel to a triangle's side splits ab into lengths of x − 6 and x + 1. the other side, ac, is split into lengths of x and x + 21. what is the length of ac?
a)27
b)33
c)39
d)45
explain how you solved. do not comment unless you are sure you know the answer. i will give you brainliest for right answer.

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?