He first offered 16 for a shilling, which is 9d a dozen. With two thrown in, 18 for a shilling is 8d a dozen, a penny less.
In old money a shilling is 12 pence. I paid a man a shilling for some apples, but they were so small I made him throw in two more. That made them cost a penny a dozen less than his first price. How many apples did I get for my shilling?
Give me a hintThe hint
Work in pence per dozen.