13.
(5/100)× 880= 44 lei (reducerea)
pretul dupa reducere: 880-44= 836 lei
14. (5/100)×5500=275 lei (marirea)
pretul dupa marire: 5500+275=5775 lei
15.
a) (x/100)×25=20
x/4=20
x=80% baieti
b) prima modalitate: 100-80=20% fete
a doua modalitate: 25 elevi-20 baieti=5 fete
(x/100)×25=5
x/4=5
x=20% fete
16. grau: (3/8)×1600= 3×200=600 hectare grau
legume: (40/100)×1600= 6400 hectare legume
floarea-soarelui: 1600-(600+640)=1600-1240=360 hectare floarea-soarelui
