A man purchases two clocks A and B at a total cost of Tk. 650. He sells A with a 20% profit and B at a loss of 25% and gets the same selling price for both clocks. What are the purchasing prices of A and B respectively?

Let
selling price  for both clocks is x taka

Purchasing price of A is = x/1.2 taka
Purchasing price of B is = x/0.75 taka 

Now
(x/1.2) + (x/0.75 ) = 650 
⇒ (100x/120) + (100x/75) = 650 
⇒ x/120 + x/75 = 650/100 
⇒ x (5 + 8)/600 = 650/100 
⇒ x = (650 × 600)/ (100 × 13) 
= 300 Taka 

Purchasing price of A is = x/1.2 taka = 300/1.2 taka = 250 taka
Purchasing price of B is = x/0.75 taka = 300/0.75 = 400 taka