I need help determining what the five rules of law that could be argued in the following scenario. And maybe some ideas on what each party could argue.. It's a research project and I just need help determining what to research. Thanks in advance and let me know if you need clarification.

On March 15, 2019, Shaggy Rogers turned seventeen.For his birthday, Shaggy's parents (who were very wealthy) gave him a fully restored 1964 Ford Mustang Convertible. "Zoinks!" exclaimed Shaggy. "Thanks mom and dad - you're the best!".

To thank his parents, Shaggy decided to have their home painted. Shaggy contacted Scooby Doo Painting, a professional painting company, and offered to pay them $10,000 to paint his parents' home, so long as the paint job was completed by April 15, 2019 (Shaggy's parents would be out of town, and he wanted to surprise them with a fresh coat of paint on the family home).

On March 17, 2019, Daphne Blake, one of the lead painters with Scooby Doo Painting, traveled to the Roger's home (located at 1225 Rich & Famous Drive in Bellingham, Washington) to look at the work that needed to be done. After spending a half hour taking measurements, Daphne told Shaggy, the paint job would cost $15,000. Shaggy, having no idea what painters actually charge, agreed, but insisted that Daphne complete the work by April 15th."Sure, no problem, I'll get it done" said Daphne."By the way, kid, you look awfully young. Are you sure you're old enough to agree to the paint job?" Shaggy said, "sure, I'm 20 years old". Daphne thought, "Hmm. I wonder if that's true", but saw that Saggy was tall and had a beard, and so assumed he was telling the truth.

Daphne asked for $5,000 up front and the reminder upon completion. "That's a lot of money" said Shaggy. "Can I give you $3,000 now and make monthly payments of $300 until the balance is paid?" Daphne agreed. Shaggy gave Daphne $3,000. The two then signed a contract for the balance. In the contract, Shaggy agreed to pay $300 on the 25^th of each month until the balance was paid in full.

On April 2, 2019, Daphne returned to the Rogers' home and began painting.Daphne spent the next ten days prepping and painting, finishing on the 12th.

Shaggy kept his word, making $300 payments from April 25, 2019 through February 25, 2020. However, on March 22, 2020, Shaggy telephoned Scooby Doo Painting, and told them he was only 17 (a minor) when he agreed to the painting contract. He then demanded they refund all of the money he had paid thus far and to cancel the balance of the contract. He ended the call saying, "That's what you get for not verifying my age!"

On April 1, 2020, Scooby Doo Painting hired an attorney and then sued Shaggy Rogers for breach of contract. What is the likely outcome? Make sure you fully analyze each party's arguments.