Could someone please answer on all 3 parts and tell me how I am supposed to solve this? I am heavily confused on this problem and there is no reference given by my professor.

019 (part 1 of 3) 10.0 points An open vertical tube has water in it. A tuning fork vibrates over its mouth. As the water level is lowered in the tube, the fifth resonance is heard when the water level is 76.5 cm below the top of the tube. 76.5 cm What is the wavelength of the sound wave? The speed of sound in air is 343 m/s. Answer in units of cm. 020 (part 2 of 3) 10.0 points What is the frequency of the sound wave; i.e., the tuning fork? Answer in units of s-1.The water continues to leak out the bottom of the tube. When the tube next resonates with the tun- ing fork, what is the length of the air column? Answer in units of cm