We have this equation. Lets take it step by step.
-10 = -6 + 2c (first add 6 to both sides. to isolate the c to be alone.)
+6 = +6 + 2c ( The 6's on the right side cancel out and we solve on the left.)
-4 = 2c ( now divide both sides by 2 to isolate the c to be alone)
÷ 2 = ÷2 ( the right side cancels out and we solve the left)
-2 = c
So our final answer is
c = - 2
:)