Răspuns :
f+m=120
f=20/100*m=1/5*m=m/5
m/5+m=120 aducem la acelasi numitor
m+5m=600
6m=600
m=100
f=100/5=20
f=20/100*m=1/5*m=m/5
m/5+m=120 aducem la acelasi numitor
m+5m=600
6m=600
m=100
f=100/5=20
notam cu b barbatii si cu f femeile
b+f=120
f=20/100*b
b+20/100*b=120
aducem la acelasi numitor
(100b+20b)/100=120
120b=12000
b=12000/120
b=100
f=100+20
f=120
b+f=120
f=20/100*b
b+20/100*b=120
aducem la acelasi numitor
(100b+20b)/100=120
120b=12000
b=12000/120
b=100
f=100+20
f=120