print的时候报错：TypeError: unsupported operand type(s) for /: 'str' and 'int'

python里用print的时候报错

seconds = 100
print('Total time: %.1f minutes'%seconds/60)

完全不明白为什么出错了，错误信息是

TypeError: unsupported operand type(s) for /: 'str' and 'int'