Răspuns :
ex 9.
b=baieti
f=fete
x=nr elevilor
b+f=x
b=3x/5
f=12
3x/5+12=x
12=x-3x/5
12=2x/5
x=12·5/2
x=30 elevi
b=3·30/5
b=18 baieti
ex 10
3/5=x/20
x=3·20/5
x=3·4
x=12
Succes!
ex 9.
b=baieti
f=fete
x=nr elevilor
b+f=x
b=3x/5
f=12
3x/5+12=x
12=x-3x/5
12=2x/5
x=12·5/2
x=30 elevi
b=3·30/5
b=18 baieti
ex 10
3/5=x/20
x=3·20/5
x=3·4
x=12
Succes!