Safin has x eggs. He sells 12 of them at a profit of 10 percent and the rest of the eggs at a loss of 10 percent. He made neither profit nor a loss overall. Which one of the following equals x?

Let a Tk be the cost price of each egg to Shafin.
Hence, the net cost of the x eggs is ax Tk.
Now, the selling price of the eggs when selling at a 10% profit is a{1 + (10/100)}
= 11a/10.
Selling 12 eggs now returns 12(11a/10)Tk.
The selling price of the eggs when selling at a 10% loss is a{1 - (10/100)}
= 9a/10.
Selling the remaining (x - 12) eggs now returns (x - 12)(9a/10)
= a(.9x + 2.4)
Since overall he made neither a profit nor a loss, the returns equals the net cost.
So we have a(.9 + 2.4)
= ax.
Dividing both sides by a yields .9x + 2.4 = x.
Multiplying each side by 10 yields 9x + 24 = 10x.
Subtracting 9x from both sides yields x = 24.