A man lost Rs 3 on every bottle of medicine he sold. Find his gain on selling 7 bottles of this medicine?

Answer 1

If he loses "Rs 3" on every bottle, there is no gain. Have you omitted some data?

Answer 2

In our textbook it's -Rs12
So what is the formula for finding the answer

Answer 3

His gain on selling one bottle is -3, sohis gain on selling x bottles is just

-3x

Now plug in x=7

I get -21, not -12.