Answer:
<em>The cost price of the article was Nu 1,000</em>
<em>The original selling price was Nu 1,120</em>
<em>The second selling price was Nu 1,200</em>
Step-by-step explanation:
<u>System of Equations</u>
Let's call:
x = Original selling price of the article
y = Cost of the article
The first condition implies that the difference between the selling price and the cost price (the profit) is 12%. Recall the profit % is always calculated with respect to the cost, that is, the profit at the first condition is:
0.12y = Original profit
Setting up the equation, we have:
![x-y=0.12y](https://tex.z-dn.net/?f=x-y%3D0.12y)
The second condition states the selling price is 80 Nu more than before, that is:
x+80= Second selling price of the article
y = Cost of the article (it doesn't change)
The profit of this condition is 20%, thus:
0.2y = Second profit
This produces a second equation:
![x+80-y=0.2y](https://tex.z-dn.net/?f=x%2B80-y%3D0.2y)
Let's put both equations together to form a system of equations:
![x-y=0.12y](https://tex.z-dn.net/?f=x-y%3D0.12y)
![x+80-y=0.2y](https://tex.z-dn.net/?f=x%2B80-y%3D0.2y)
Operating on both equations:
![x=1.12y](https://tex.z-dn.net/?f=x%3D1.12y)
![x=1.2y-80](https://tex.z-dn.net/?f=x%3D1.2y-80)
Equating both equations, we have an equation with only y's:
![1.12y=1.2y-80](https://tex.z-dn.net/?f=1.12y%3D1.2y-80)
Subtracting 1.2y on each side:
![1.12y-1.2y=-80](https://tex.z-dn.net/?f=1.12y-1.2y%3D-80)
Operating:
![-0.08y=-80](https://tex.z-dn.net/?f=-0.08y%3D-80)
Solving:
![\displaystyle y=\frac{-80}{-0.08}=1,000](https://tex.z-dn.net/?f=%5Cdisplaystyle%20y%3D%5Cfrac%7B-80%7D%7B-0.08%7D%3D1%2C000)
a)
The cost price of the article was Nu 1,000
b) The selling price of the article will be calculated in both cases:
Original selling price: x=1.12y= 1.12*1000=1,120
The original selling price was Nu 1,120
The second selling price was x+80=1,200
The second selling price was Nu 1,200