What is the period of y=-5cos(pi/8x)+3

The number if marbles of different colors stored in a hat is listed below: 4 red marbles 10 green marbles 7 blue marbles. without looking in the hat, dan takes out a marble at random. he replaces the marble and then takes out another marble from the hat. what is the probability that dan takes out a blue marble in both draws?

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

Javier bought a painting for $150. each year, the painting's value increases by a factor of 1.15. which expression gives the painting's value after 77 years?