You need your dad to teach you business. Ask about "maximizing profit" -- he seems excellent at this.

While it was dishonest of Dad to claim the job was a free one for a friend, he apparently lived up to what you expected at the time - Food and a chance to work with your dad. But what you should ultimately take away from this is the skill and practice of how to make a living working. When I was very young, my dad was a projectionist at a drive in movie theatre. Besides seeing all movies free, my lifelong fascination with electronics came from being with and helping my dad do the maintenance on the projector and sound system. Later Dad switched over to air conditioning and appliance repair and installation. I tagged along during summers as Dad’s helper. I do not recall being paid for much of that besides an allowance and my lunch. But what I learned from that was something about electricity, appliances, and air conditioning units. And I learned by watching and listening how to run a small business. I became an electronic engineer, but my personality was highly influenced by the things I learned working with my dad. You never lose that… I suggest that you be respectful, but honestly discuss with Dad how much you should be paid to do the work you do. Bear in mind Dad has a lot more expenses than you, so be reasonable. In the future you should identify up front if you are going to be paid or not to work with Dad. In the end you and Dad need to come to some sort of understanding.

That's a scandal. It should have been at least pizza and a beer.