50 point come on smart guys​

What is the missing reason in the proof? segment addition congruent segments theorem transitive property of equality subtraction property of equality?

Margie is practicing for an upcoming tennis tournament. her first serve is good 20 out of 30 times on average. margie wants to know the estimated probability that her first serve will be good at least four of the next six times she serves. how could she design a simulation for this scenario?

The slope of the line whose equation is y - 3 = 0 is 0 3 no slope