if the cost price of 10 items is equal to the selling price of 8 items , then what will be the percentage profit.

20%

Step-by-step explanation:

Let's say that the 10 items cost $1 each. That would mean you spend $10.

As of that, the cost of 8 items (selling price) is also $10, meaning that you would spend $1.20 to buy the item

($1.20 - $1)/($1) = .20/1 = 1/5 = 20%

the answer to the question is a  

it has the same slope and the same y-intercept.