What is a diagram used to show the total number of possible outcomes in a probability experiment

Aline passes through (1,-5) and(-3,7) write an equation for the line in point slope form rewrite the equation in slope intercept form

Sanjay solved the equation below. which property did he use to determine that 7x+42=42 is equivalent to 7(x+6)=42 7x+42=42 7x=0 x=0

Can anyone explain to me how to do this? anything will .