The frequencies differ by 5 Hz. This is because her beats occurs 5 times per second. As she turned the tuning knob, which resulted in a reduction of tension. The decreased speed of wave on the spring also reduces its frequency.
In all, the original frequency has to be higher than 440 Hz. And since she heard 5 beats per second before turning the knob. Her original frequency is 440 Hz + 5 Hz = 445 Hz