In solving the equation 2x+5=9, which property of equality do we use first? Why?

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?

Ineed in figuring out this problem.

An equation in slope-intersept form the lines that passes thought (-8,1) and is perpindicular to the y=2x-17.