An organ pipe open at both ends has a harmonic with a frequency of 464 . The next higher harmonic in the pipe?

An organ pipe open at both ends has a harmonic with a frequency of 464 . The next higher harmonic in the pipe has a frequency of 522 Hz. Find the frequency of the fundamental. Also, find the length of the pipe. Please help, I have no idea how to solve this problem! Any help is greatly appreciated.