To find the profit or loss, we need to calculate the total cost price (CP) and the total selling price (SP) of the toffees.

The CP can be calculated by adding up the number of toffees bought by each customer: CP = 10 + 15 + 20 + 25 + 30 = 100

Since the shopkeeper makes a 20% profit, the SP can be calculated by adding 20% of the CP to the CP: SP = CP + 0.2 * CP = CP * 1.2

If the person who forgot to pay had paid his amount, the SP would have been: SP_with_payment = SP + 20 = CP * 1.2 + 20

Now, let’s calculate the profit or loss: Profit/Loss = SP_with_payment - CP

Substituting the values: Profit/Loss = (CP * 1.2 + 20) - CP Profit/Loss = 0.2 * CP + 20

To determine the percentage profit or loss, we need to divide the Profit/Loss by the CP and multiply by 100: Percentage Profit/Loss = (Profit/Loss / CP) * 100

Substituting the values: Percentage Profit/Loss = (0.2 * CP + 20) / CP * 100 Percentage Profit/Loss = (0.2 + 20/CP) * 100

Now, let’s calculate the percentage profit or loss: Percentage Profit/Loss = (0.2 + 20/100) * 100 Percentage Profit/Loss = (0.2 + 0.2) * 100 Percentage Profit/Loss = 0.4 * 100 Percentage Profit/Loss = 40%

Therefore, the correct answer is 40% loss.