Johan is selling baseball cards for 12$ each. he is selling 8 cards and says hell make it 8$ how is it reasonable if the awnser is correct

Assuming you meant...

'Johan is selling baseball cards for 12$ each. He is selling 8 cards and says he'll make 8$ profit. How is it reasonable if the answer is correct?'

The answer is reasonable if he is only making a $1 profit per baseball card. For example if he bought the baseball cards for $11 and is selling them for $12, than he only makes $1 for every cards sold. If he sells 8cards, he'll make an $8 profit.