Final answer:
If Sunayna bought the pen for Rs 20 and sold it for Rs 22.80 to maintain a 20% profit margin, her actual profit would be Rs 2.80, resulting in a profit percentage of 14%.
Step-by-step explanation:
The student's question concerns profit or loss percentage calculation, which is a fundamental topic in Mathematics dealing with financial arithmetic. If Sunayna bought a pen for Rs 19 and sold it at 20% profit, her selling price would be Rs 19 + (20/100) × Rs 19 = Rs 19 + Rs 3.80 = Rs 22.80.
If Sunayna bought the pen for Rs 20 and sold it for Rs 22.80 to maintain a 20% profit margin, her actual profit would be Rs 2.80, resulting in a profit percentage of 14%.
If she had instead bought it for Rs 20, to maintain the same profit margin, her selling price would still be Rs 22.80. Thus, the profit in this case would be Rs 22.80 - Rs 20 = Rs 2.80, and the profit percentage would be (profit/cost price) × 100 = (Rs 2.80/Rs 20) × 100 = 14%.