Mariko spent 2 1/2 hours or less doing Spanish and history homework last night. She spent at least 3/4 hour on history, and she spent more time in Spanish in history. Which system of equalities represents the time Mariko spent on homework if X represents the number of hours spent on Spanish NY represents the number of hours spent on history?

Two numbers have a sum of -19. one number is x. what expression represents the other number?

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?

The area (a) of a circle with a radius of r is given by the formula and its diameter (d) is given by d=2r. arrange the equations in the correct sequence to rewrite the formula for diameter in terms of the area of the circle.