# Question 91068

Jan 17, 2015

First set up a buy-sell-profit equation per orange.

One orange will cost $\frac{30}{20} = 1.50$ RS

Selling will get you $\frac{27}{12} = 2.25$ RS per orange

(Profit per orange is then $2.25 - 1.50 = 0.75$ RS)

And the gain% will be:

("sell"-"buy")/"buy"=(2.25-1.50)/1.50=0.75/1.50=0.50=50%#

Extra
There are short-cuts if you realise that a score = 4x5
And a dozen = 4x3. You can find these out for yourself.
But the above is the way that always works, even if the selling quantity is way different from the buying quantity.

BTW 15 dozen will give a net profit (in RS) of:
$15 \cdot 12 \cdot 0.75 = 180 \cdot 0.75 = 135$ RS