I am given the following two equations as models for male and female population

$\dfrac {df} {dt}$ = $\dfrac {mf} {m+f}$$B\_f-fD\_f$

$\dfrac {dm} {dt}$ = $\dfrac {mf} {m+f}$$B\_m-mD\_m$

assume $D\_m$=$D\_f$=$D$

The equilibrium points two the previous two equations form a line in the $f-m$ plane and I am trying to find the equilibrium ratio of $m/f$

I have tried moving everything to one side for both of them and then integrating and solving for $m$ and $f$ respectively but it seems to just get more complicated