Answer:

Explanation:
First we find the slope. The formula for slope is

Using our two points, we have
m = (q--q)/(p--p) = (q+q)/(p+p) = 2q/2p = q/p
Point-slope form of an equation is

Using the first point as (x₁, y₁) and our value for m, we have
y - -q = (q/p)(x - - p)
y + q = (q/p)(x + p)
Using the distributive property, we have
y + q = (q/p)x + (q/p)p
y + q = (q/p)x + (q/p)(p/1)
y + q = (q/p)x + qp/p
y + q = (q/p)x + q
Subtract q from each side:
y + q - q = (q/p)x + q - q
y = (q/p)x