The answers to the questions
Point s should be at 6,-2 and you have plotted at 6,2.
then, the line y=x goes from bottom left corner, through the origin to the top right corner. reflect your shape in this.
Answer:
1) Given
2) if lines are parallel, then corresponding angles are equal
3) Substitution
4) if altenate interior angles are equal, then the lines are parallel