Mother, I'm going to pay you for the upbringing I owe you.

But first I need to charge you because you owe me more!

So far, 20 years of service as your utility man have been under your strict command.

20 years but only 15 I will charge you.

Mother, this is the bill you have to pay me:

For shopping, errands, housework, I will charge you 10 dollars per day, which multiplied by 30 would be 300 per month. and 300 for 12 months would give 3,600 per year.

That annual amount multiplied by 15 tells us that you must pay me a total of exactly $54,000.