We can use the Binomial Theorem to expand (2u−3v^3)^5 as follows:
(2u−3v3)5=(50)(2u)5(−3v3)0+(51)(2u)4(−3v3)1+(52)(2u)3(−3v3)2+(53)(2u)2(−3v3)3 +(54)(2u)(−3v3)4+(55)(−3v3)5 =32u5+120u4v3−216u3v6+216u2v9−90uv12+27v15.The coefficient of u^2v^9 is therefore −216.