How to calculate profit and loss

I have a trading account in 5paisa. (cost cutting per order is Rs.10/-)

example :
if i am buying a 100 quantities of stocks of Rs. 500/- each .
100 * 500 = 50000/-

and if i sell those stocks at 512/- , now how to calculate the profile .

&& if i sell those stocks at 450/- , now how to calculate the loss.

I saw many youtube trading videos , the calculations were different .

can some one tell me how to calculate the profile and loss with this example.
In 3rd standard,My teacher asked me-
Rivi,Suppose you buy 100 chickens at 500rs each and sold them all at 512rs,how much will be your Profit??
I failed to answer that,because at the age of 8,I was very poor in maths :( She gave me Murga Bano punishment..

Later I understood that 12rs is a Profit on each chicken,so on 100 chicken I sold,my profit will be 1200Rs...Now I have to deduct some carting charges(Brokerage) too to get a Net Profit.

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