一次環保知識競賽共有25道題，規定答對一道題得4分，答錯或不答一道題扣1分.在這次競賽中，小明被評為優秀（85...

問題詳情：

一次環保知識競賽共有25道題，規定答對一道題得4分，答錯或不答一道題扣1分.在這次競賽中，小明被評為優秀（85分或85分以上），小明至少答對了幾道題？

【回答】

解：設小明答對了x道題，·············································································· 6分

4x－(25－x) ≥85····························································································· 8分

x≥22····························································································· 9分

所以，小明至少答對了22道題.····································································· 10分

知識點：不等式

題型：解答題