Quantitative aptitude-profit and loss A merchant earns 25% profit in general
Once his 25% consigment was abducted forever by some goondas. Trying to compensate his loss he sold the rest amount by increasing his selling price by 20%.What is the new percentage profit or loss ?
A.10% loss 
B.12.5% loss
C.12.5% profit 
D.11.11% loss

I took Initial CP as 100,so selling price after profit is 125 
After 25% abduction,75 is available whose CP is 100 and SP is 125+50= 150 
So 150-100/100=50% 
But the answer is wrong.
What mistake have I done ?
Let the merchant had =100 product with total CP =100
Whose SP = 1.25 *100 = 125
In 2nd Case the price of 75 product = 125/100 *75 =375/4
New SP = 1.20*375/4 = 112.5
So profit = 112.5 - 100 = 12.5 
profit percentage = 12.5/100 = 12.5%
Assume that the merchant was purchasing 100 goods at 100 Rs. each. He was selling them at 25% profit for 125 Rs. each.

His total profit = Total Selling Price - Total Cost Price = 100*125 - 100*100 = 2500 Rs. 

Now, 25% of his good have been abducted. So, he is left with 100 - 25 = 75 goods

He increased his selling price by 20%. New selling price = 1.2 * 125 = 150 Rs.

Total money he makes now = 75*150 = Rs. 11250 

His new profit = 11250 - 10000 = Rs. 1250

New percentage profit = (1250 / 10000) * 100 = 12.5 % (Option C)

You can check out some basic concepts of profit and loss here.