A nurse mixes 40 cc of 60% saline solution with a 30% solution to produce a 35% salone solution How much of the 30% solution should he use?

Pls i’m too dumb to know what i’m doing right now

What is the measure of ac? 5 units 13 units 26 units 39 units 3x- 2b 6x + 9

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?