Suppose I have a coke can
Now,
Suppose I purchased the can for Rs 20 and sell it for Rs 20. What is my profit or loss?
Now,
CP = Rs 20
SP = Rs 20
So,
CP = SP
Profit or Loss = CP − SP
= 20 − 20
= 0
So, when
Cost Price = Selling Price
There is no Profit, no Loss