The degree of a polynomial is the highest power of its terms. The power of a term is the sum of the powers of all the variables in a term. A polynomial is written starting with the greatest power in standard form. In the first case, the power of the first term is 3, the power of the second is 3 (2 from x + 1 from y) but the power of x has decreased so it is the second term, and then so on. In the second case, the power is starting form 2 and then increasing to 3. This is incorrect. Therefore, Marcus' suggestion is correct.
They are both correct because there is more than one way to write a multivariable polynomial in standard form. Marcus has the exponents on the x variable in descending order from the highest degree to the lowest degree. Ariel has the exponents on the y variable in descending order from the highest degree to the lowest degree.
You can paraphrase your answer and you should be fine.
