python 2中的3个无效语法错误

Question

大家好，我想用python做一个贷款计算器，但我不明白为什么会出现3个语法错误，都是因为变量firstOperation

interestRate = raw_input("Annual interest rate: ")
paymentsPerYear = raw_input("Number of payments per year: ")
length = raw_input("Length of the loan in years: ")
interest = float(interestRate)/float(paymentsPerYear)
presentValue = raw_input("Present Value: ")
firstOperation = interest*float(presentValue)
secondOperation = 1-(1+interest)**-(float(length)*float(paymentsPerYear)
print(firstOperation)
print(secondOperation)
payment = firstOperation/secondOperation
print(payment)

Answer 1

你跟错了台词。结尾缺少)

secondOperation = 1-(1+interest)**-(float(length)*float(paymentsPerYear)