Answer
The fundamental frequency is 302 Hz.
The first overtone is 604 Hz.
The second overtone is 906 Hz.
Work Step by Step
We can find the speed $v$ of the wave as:
$v = \sqrt{\frac{F_T}{\mu}}$
$v = \sqrt{\frac{F_T}{m/L}}$
$v = \sqrt{\frac{520~N}{0.0034~kg/0.92~m}}$
$v = 375~m/s$
We can find the fundamental frequency using the formula below. Note that $L = 0.62~m$ from the bridge to the support post.
$f_1 = \frac{v}{2L}$
$f_1 = \frac{375~m/s}{(2)(0.62~m)}$
$f_1 = 302~Hz$
We can find the first two overtones as:
$f_2 = 2~f_1 = (2)(302~Hz) = 604~Hz$
$f_3 = 3~f_1 = (3)(302~Hz) = 906~Hz$