A2. Tonček has written out the third power of the expression $2 x^{3} y-3 x y^{2}$. He noticed that in one of the terms, the exponents of the bases $x$ and $y$ are equal. What is the coefficient in this term?
(A) 36
(B) -36
(C) 18
(D) -54
(E) 54
A2. $\left(2 x^{3} y-3 x y^{2}\right)^{3}=\left(2 x^{3} y\right)^{3}-3\left(2 x^{3} y\right)^{2} \cdot\left(3 x y^{2}\right)+3\left(2 x^{3} y\right) \cdot\left(3 x y^{2}\right)^{2}-\left(3 x y^{2}\right)^{3}=8 x^{9} y^{3}-36 x^{7} y^{4}+$ $54 x^{5} y^{5}-27 x^{3} y^{6}$. The third term has equal exponents for $x$ and $y$, the desired value is 54.