What does writing 8x mean.

At diana's closet, 1/6 of the clothes are white and another 7/12 are black. what fraction of the clothes is either black or white?

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?

Which is the focus of a parabola with equation y2=4x