Solving Equations to Find Profit

Date: 8/10/96 at 4:22:5
From: Anonymous
Subject: Solving Two Equations to Find the Profit of...

You bought A and B for 40,000 Won. You sold A for a 0.3 percent 
profit, and sold B at a 0.2 percent discount. You profited 5000 Won. 
What was A's original price?

*Won-Korean money measurement.
Thanks a lot!

Date: 8/30/96 at 17:42:23
From: Doctor Jerry
Subject: Re: Solving Two Equations to Find the Profit of...

Let A equal the original price of A and B equal the original price of 
B. So, one equation is A + B = 40000.

If A was sold for 0.3 percent profit, then the profit is A - A*0.003; 
if B was sold at a 0.2 percent discount, then the profit will be B*
0.998 - B.  So, a second equation is A - A*0.003 + B*0.998 - B = 5000.

If these equations are solved simultaneously, then A = 5085.09 
(rounded to six significant figures).

You will need to look at how I interpreted the 0.2 percent discount.  
I took this to mean that B was sold at a price of 100 - 0.2 percent of 
value.  So the selling price was B*(100-0.2)/100 and the profit is 
B*0.998 - B, which is a negative profit.

-Doctor Jerry,  The Math Forum
 Check out our web site!  http://mathforum.org/dr.math/