Which property justifies his first step? ?

The general form of the quetion of a circle is ax^2+by^2+cx+dy+e=0 where a=b=0 if the circle has a radius of three units and the center lies on the y axis which set of values of a, b, c, d, and e might correspond to the circle

There are a total of 75 students in the robotics club and the science club. the science club has 11 more students than the robotics club. how many students are in the science club?

Q= {1.7, 1.1, 1.4, 2.1, 2.3, s}. what is the absolute difference between the greatest and least possible values of the median of set q? express your answer as a decimal to the nearest hundredth.