The people in this class are doing a school trip! [br]We are going to El Picacho mountain, in Alcalá de los Gazules.[br]The high school gives us 21 sandwiches in total. The class is divided into three groups:[br][br]1) Five are going to the lake.[br][br]2) Six are going walking in the mountain.[br][br]3) Four are going to see the waterfall.[br][br]Now, we need to share the sandwiches... but every person should get the same amount of sandwich![br][br][b]How many sandwiches should we give to each group?[/b][br][br]([i]Tip: You can break the sandwiches into pieces... but how many pieces?)[br][/i][br]BONUS: What if we only have 13 sandwiches?