Frequency of a Relaxation Oscillator IC
calculate the upper and lower switching threshold voltages that will be applied to -IN during charging and discharging cycles respectively. You can ignore the capcaitor and upper 100kΩ resistor for ths step. Just assume output high (high Z because it's an OC Output) and output low (-15V).
calculate charge time during which \$V_C\$ is going from lower to upper threshold voltage and discharge time during which \$V_C\$ is going from upper to lower threshold voltage (the times are not exactly the same because equivalent series resistance of R network for charging is 104.7kΩ and for discharging it is 100kΩ). If you don't need high accuray (better than 5%) you can assume that both are about the same and half the calculation effort.


Get frequency as inverse of sum of charging and discharging time.