Calculate the equilibrium points and analyze ther stability given the following equation

$S^{\text{'}}=g(K-S-I)-B.BS$

$I^{\text{'}}=B.BS-I$

$B^{\text{'}}=rSB-B$

$[$Hint first equilibuin puit is $S=k,I=0,B=0$ This will help you determine the second equiliorm point.