Math
posted by Smartypants on .
Mr lol bought x oranges for $30 and sold them at a profit of 5cents per orange. Write down the (i)cost price of an orange.
(ii)the selling price of an orange
When he had sold all except 20 of the oranges, he found he had received $28.
(iii) form an equation in x and show that it simplifies to xsquare + 20x 12000= 0

1. Cost = $30/X per orange.
2. Selling Price = (30/X+0.05)per orange.
3. (30/X + 0.05)(X  20) = 28,
Multiply the 2 binomials and get:
30  600/X + 0.05X  1 = 28,
Multiply both sides by X:
30X  600 + 0.05X^2  X = 28X,
0.05X^2 + 29X  600 = 28X,
0.05X^2 + 29X  28X  600 = 0,
0.05X^2 + X  600 = 0,
Multiply both sides by 20:
X^2 + 20X  12000 = 0. 
But your solution of this problem doesn't show the stuff that any real businessman would want to know. How many oranges? What is my unit cost in actual cents not formula? When will I be in profit? etc

Thanks a lot Henry! Your working is right!
Btw, thank too Raymond for helping me out, I appreciate it a lot (: 
Appreciate both of you who help me! Thanks!!!!!

Btw Henry, why multiply by 20 in the end? Is it because he had sold all except 20 of the oranges?