Answer:
m = (y - c)/x
Explanation:
Given :
y = mx + c
=============================================================
Subtract c from both sides :
⇒ y - c = mx + c - c
⇒ y - c = mx
=========================================================
Divide both sides by x :
⇒ mx/x = (y - c)/x
⇒ m = (y - c)/x