为计算机科学做一些编码作业，但我一辈子都搞不懂

Question

#Alrighty lets give this a shot.
#So it no longer works and i can't figure out why....

coach = 550
entry = 30
students = 45
maxstudents = 45
discount = 0
moneydiscount = 0
cost = 0
studentcost = 0

Run = True

while Run == True:

    students = int(input("Please input number of students going on the trip:"))
    if students > 45 or students <=0:
        print("Wrong number of students detected. Please consult your Principal or try again.")
    elif students < 45:
        print("Number of students =")
        print(students)
        print("The cost per student will be:")
        ticket_cost = (students * 30)
        num_free_tickets = int(students / 10)
        moneydiscount = (num_free_tickets * 30)
        cost = str(round(coach + ticket_cost - moneydiscount, 2))
        studentcost = str(round(5 + cost / students, 2))
        profit = (students * 5)
        #this makes sure it is in payable amounts^
        print(student_cost)
        print("profit is:")
        print(profit)
    else:
        print("This input is not numerical, please only insert numerical values")

它给了我这个错误： 回溯（最近一次呼叫）： 文件“C:\Users\littl\Desktop\Folders\Home Ed Work\Computer Science\Python homeography Post-Summer\06-11-17\学生.py“，第28行，in studentcost=str（轮（5+成本/学生，2）） TypeError:不支持/：“str”和“int”的操作数类型

所以我知道这和： studentcost=str（轮（5+成本/学生，2））

但是因为上面这条线几乎是一样的，我不知所措。。。你知道吗

Answer 1

str()创建一个文本字符串，不能对其进行数学运算。例如，您需要整数类型。在你的情况下，你已经有了：

cost = round(coach + ticket_cost - moneydiscount, 2)
studentcost = round(5 + cost / students, 2)

如果文本中包含数字，则可以将其转换为：

some_value = int("1")