Using the substitution P=1/x and Q=1/y. solve the simultaneous equation 2/x + 1/y=3 and 1/x - 5/y=7

Write the equation in logarithmic form e^x=403.429

Find two numbers if their sum is 91 and the ratio is 6: 7?

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?