500
There are x buckets with y gallons in them, represented by the equation x=2y. If 1 unit on the x-axis represents 1 bucket, and 1 unit on the y-axis represents 2 gallons, and x<10, where the greatest number x can be is represented by point P, the origin is represented by point O, and the end of the x-axis is represented by point N, find the angle of line NOP. Remember that the x-axis and y-axis make a 90º angle.
What is a 45º angle?