Ifede can use a limited number of spells to defeat trolls and goblins. It takes the same number of spells to defeat each troll, and it takes 3 spells to defeat each goblin. Let T represents the number of trolls and G represents the number of goblins that Ifede can defeat without running out of spells. 5T+3G≤855 According to the inequality, how many spells does it take to defeat each troll, and what is the maximum number of spells that Ifede can use?