import math
def loan_calc():
    x = input('What are you gonna calculate? ')
    if x == 'r' or x == 'R':
        t = input('How long is the period in years? ')
        pv = input('What is the present value? ')
        fv = input('What is the future value? ')
        print('{} euqals to {}'.format(x, pow(fv/pv, 1/t)-1)
    if x == 'p' or x == 'P':      (这一行总是提示语法出错,如果删除的话就提示下一个if行语法出错)
        r = input('What is the interest rate? ')
        pv = input('What is the present value? ')
        fv = input('What is the future value? ')
        print('{} euqals to {}'.format(x, log(1+r, fv/pv)))
    if x == 'pv' or x == 'PV':
        r = input('What is the interest rate? ')
        t = input('How long is the period in years? ')
        fv = input('What is the future value? ')
        print('{} equals to {}'.format(x, fv/pow(1+r, t)))
    if x == 'fv' or x == 'FV':
        r = input('What is the interest rate? ')
        t = input('How long is the period in years? ')
        pv = input('What is the present value? ')
        print('{} equals to {}'.format(x, pv*pow(1+r, t)))
loan_clac()

标点符号都没有问题,都检查过了

谢谢你,问题解决了!