please explain the steps. thanks!

$2\mathrm{.}30$ Calculate the force $f_y$ applied perpendicularly to the rigid lever $OC$ at $B-$see Figure $2\mathrm{.}61-$that generates a displacement $y_c=0\mathrm{.}01m$ for $k_1=80\frac{N}{m},k_2=150\frac{N}{m},k_3=40\frac{N}{m},$ and $k_4=30\frac{N}{m}.$ The lever undergoes small rotations around the axis passing through the pivot $O.$

FIGURE $2\mathrm{.}61$

Small$-$Rotation Pinned Lever With Attached Springs and Force.