Rewrite 1/-3/6^x in simplest radical form

Does anyone know how to do geometryme with this problem

Awoman has 14 different shirts: 10 white shirts and 4 red shirts. if she randomly chooses 2 shirts to take with her on vacation, then what is the probability that she will choose two white shirts? show your answer in fraction and percent, round to the nearest whole percent.

Lines a and b are perpendicular. the equation of line a is y=13x+3. what is the equation of line b?