Question

intr-o sala de spectacol sunt cativa copii,femei de 4 ori mai multe,iar barbati cu 9 mai multi decat femei.stiind ca in total sunt 189 de persoane,afla cati barbati sunt.

Answer 1

$c+f+b=189 \\\\ f=4c \\\\ b=f+9= 4c+9 \\\\\\ c+4c+4c+9=189 \\\\ 9c=189-9 \\\\ 9c=180 \ \ \ |:9 \ \\\\ \boxed{c=20 \ (copii) } \\\\ f=4*20 \\\\ \boxed{f=80 \ (femei)} \\\\ b=80+9 \\\\ \boxed{b=89 \ (barbati)}$

Answer 2

a+b+c=189 , a= copii /-----/, b=femei /-----/-----/-----/-----/, c= barbati /-----/----/-----/-----/+9 , sau b=4a si c=4a+9 , aflam cate pers ar fi daca barbatii ar fi egali cu femeile 189- 9= 180 pers, adunam segmentele =9 si aflam un segm 180:9=20 (a) , aflam b . b=4*20=80 , aflam c. c=80+9=89; verificare 20+80+89=189