Kinda forgot how to do this but i got 894.09 for my answer not sure if im right

Three times the sum of a number and seven is negative thirty-six. what is the number?

Use composition to determine if (x) or h(x) is the inverse of f(x) for the limited domain x2-1.

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?