The first thing you should do is to graph the coordinates. Once you have graphed the coordinates, you should find the length of each side by using the distance formula given here:
You would then proceed to use standard geometry to find the area of the polygon.
Y is a vertical axis x is a horizontal axis when drawing a line, the line drawn to them is perpendicular so lines only touching the x axis are vertical and lines touching only the y axis are horizontal
It is shifted 15 units up. Think of how you're solving for y, and by adding 15 to the equation, y increases by 15. If y increases by 15 the graph shifts up by 15. Hope that helps.