What are expressions are equivalent to 6x-18y

The ph level of a blueberry is 3.1 what is the hydrogen-ion concentration [h+] for the blueberry

What is the solution to the division problem below x3+x2-11x+4/x+4

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?