A 0.0150 kg, 2.09 m long wire is fixed at both ends and vibrates in its simplest mode under a tension of 214 N. When a tuning fork is placed near the wire, a beat frequency of 5.20 Hz is heard. What are the possible frequencies of the tuning fork?

I solved for speed using square root (T/u). Then, I used the speed with the formula f = v/2L. Finally, I used fb = f1 - f2 to find the other frequency. I didn't get the correct answer.