each student in a group of 30 students studies German,Italian,or both ,The total number of studentsstuding German is three more than the total number of students studing Italian,If the number of students that study both subjects is the same as the number of students that study exactly one subjec,how many students in the group study only Italian?
问题描述：
each student in a group of 30 students studies German,Italian,or both ,The total number of students
studing German is three more than the total number of students studing Italian,If the number of students that study both subjects is the same as the number of students that study exactly one subjec,how many students in the group study only Italian?
答
设x=German,y=Italian,z=German+Italian
①.x-y=3
②.x+y=z
③.x+y+z=30
得 x= 9, y=6, z=15
so there are 6 students in the group study only Italian
答
each student in a group of 30 students studies German,Italian,or both ,意思是：单独学德语+单独学意大利语+两门都学的学生合计30人.studing German is three more than the total number of students studing I...