Question $(3)$: $(10$ points$)$ In the following $10V_{pp}$ Triangular$-$wave oscillator, if both op$-$amps should be supplied by the same power source, find the proper power supply that satisfies the oscillation conditions, given that:

$R_1=3k$

$C=10nF$

Frequency of oscillation $f_r=20kHz$

$(10$ points$)$ For the above design, a $30kHz$ frequency of oscillation is needed, which resistor among $R_1,R_2,$ and $R_3$ do you need to change to accommodate for the new $f_r$ without changing the amplitude of oscillation. What is the new value of the chosen resistor?