1) 7 kg mere....DP....... 91 lei
13 kg mere.............. ? lei
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[tex] \frac{7}{13} [/tex]=[tex] \frac{91}{x} [/tex]
x=[tex] \frac{91*13}{7} [/tex]
x=169
2) 4%= 50 kg | *25
100%= 1250 kg
3) [tex] \frac{b}{a} [/tex]:[tex] \frac{b}{c} [/tex]= [tex] \frac{b}{a} [/tex]*[tex] \frac{c}{b} [/tex]= [tex] \frac{c}{a} [/tex]= 20:5=4 => [tex] \frac{a}{c} [/tex]= [tex] \frac{1}{4} [/tex]