A shop charges a fixed delivery fee of 7 taka plus 4 taka for each eraser pack. If the total cost is 39 taka, how many eraser packs were ordered?
Note
Let x be the number of items. The equation is 7 + 4x = 39. Subtract 7: 4x = 32. Divide by 4, so x = 8. The fixed fee is not part of the item count.