How do I graph p=2-0.0025q?

We can draw this in x-y coordinate system (actually its 2D system whereit doesnt matter how we name variables I said x-y because that is some kind of standard to call that system)

when you have to draw a graph of a line (this is function of a line) you find 2 dots and than just connect them. Easiest way to do that is to make those dots on coordinate system axis.

for p=0 we will get dot on q axis and for q = 0 we will get dot on p-axis.

p=0 - > 0.0025q = 2, - > q = 2/0.0025 = 800

q=0 - > p = 2

now you have 2 dots with (p, q) coordinates

(0,800) and

(2,0)

draw axis, place these dots on them connect dots and extend line on both sides (because line doesnt have beginning nor end) and you are done.