To calculate the total postage for 105 letters, you can multiply the cost of posting one letter by the number of letters.
Cost of posting one letter = 5 kobo (which is 0.05 Naira) Number of letters = 105
Total postage = Cost per letter × Number of letters Total postage = 0.05 Naira × 105 = 5.25 Naira
So, the total postage for 105 letters will be 5.25 Naira.