點解可以 to v+ing

solving 呢個 -ing 係一個 gerund, 即係動名詞, 係將動詞當名詞用

由於to後可以用名詞 (考慮呢句 -> His effort contributed to [our success]), 所以其實成句 [solving the problems that stemmed from Madoff's misdeeds] 係當一個名詞組用

簡單而言，因為在英語的慣常用法中， "contribute to "後要用名詞性質的短句或詞組，所以題目中寫了 "solving" (把 "solve" 轉為動名詞)，或像第一位回答者用 "our success" (「我們的成功」- 名詞短句) 。