Exercitiul 4
[tex]\displaystyle{ \frac{4}{3} = \frac{5}{3} - \frac{1}{3} }[/tex]
[tex]\displaystyle{ \frac{40}{30} = \frac{60}{30} - \frac{20}{30}}[/tex]
[tex]\displaystyle{ \frac{20}{9} = \frac{27}{9} - \frac{7}{9} }[/tex]
[tex]\displaystyle{ \frac{8}{6} = \frac{19}{6} - \frac{11}{6} }[/tex]
[tex]\displaystyle{ \frac{16}{12} = \frac{20}{12} - \frac{4}{12} }[/tex]
Exercitiul 5
[tex]\displaystyle{ \frac{25}{99} - (x + \frac{3}{99}) = \frac{14}{99}}[/tex]
[tex]\displaystyle{ (x + \frac{3}{99}) = \frac{25}{99} - \frac{14}{99} }[/tex]
[tex]\displaystyle{ x + \frac{3}{99} = \frac{25-14}{99} }[/tex]
[tex]\displaystyle{ x + \frac{3}{99} = \frac{11}{99} }[/tex]
[tex]\displaystyle{ x = \frac{11}{99} - \frac{3}{99} }[/tex]
[tex]\displaystyle{ x = \frac{11-3}{99} }[/tex]
[tex]\displaystyle{ x = \frac{8}{99} }[/tex]
Exercitiul 6
a = 320
b = 25% din a
[tex]\displaystyle{ b = \frac{25}{100} \cdot a }[/tex]
[tex]\displaystyle{ b = \frac{25 \cdot 320}{100} }[/tex]
[tex]\displaystyle{ b = \frac{8000}{100} }[/tex]
b = 80
a + b = 320 + 80
a + b = 400
c = 75% din a + b
[tex]\displaystyle{ c = \frac{75}{100} \cdot (a + b) }[/tex]
[tex]\displaystyle{ c = \frac{75 \cdot 400}{100} }[/tex]
[tex]\displaystyle{ c = 75 \cdot 4 }[/tex]
c = 300
a + b + c = 400 + 300
a + b + c = 700
