A sold an article to B at a gain of 10% ,B sold it to C at a gain of 20% .If C paid Rs.2,640 for it, what did it cost A? Help me with this question please

$2,000

Step-by-step explanation:

Since B sold the article to C at a gain of 20%, 2,640 must be 120% or 1.2 times the price that B paid.

To find the price that B paid, we just need to divide 2,640 by 1.2, as the original price multiplied by 1.2 = a 20% increase.

2,640/1.2= 2,200

The price B paid for it must have been 2,200.

Now we know that 2,200 was the price sold by A to gain 10%, therefore it is 110% or 1.1 times the original price A paid for it. Therefore, once again to find the original price, we just need to divide it by 1.1:

2,200/1.1 = 2,000

The original price it cost A was $2,000.

Hope this helped!

the answer to the question is a  

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