Answer:
Because the cost price of 30 pens = Rs. 150
So, the cost price of 1 pen = 150/30 =5
so, the cost price of 20 pens =
Rs. 5 x 20 = 100
Cp is Rs. 100
Sp is Rs. 140
So, profit = 140-100 = Rs. 40
Profit % = (Profit x 100)xCp
=(40 x 100)/100
= 4000/100
= 40% profit
Explanation: