Write and solve an equation that represents the following: a number decreased by 12 is 24.
x - 24 = 12; x = 36
x - 12 = 24; x = 36
24 - 12 = x; x = 12
x + 12 = 24; x = 12

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?