a)[tex]\frac{a+3b}{5a+b}=\frac{5}{11}\Rightarrow 11(a+2b)=11a+33b=5(5a+b)=25a+5b\Rightarrow 28b=14a\Rightarrow 2b=a\Rightarrow b=\frac{1}{2}a[/tex]
Daca exprimam in procente
[tex]b=100%*\frac{a}{2}=50%*a[/tex] deci 50% intr-adevar
b)[tex]\frac{2b+c}{b+2c}=\frac{7}{5}\Rightarrow 5(2b+c)=7(b+2c)\Rightarrow 10b+5c=7b+14c\Rightarrow 9c=3b\Rightarrow \frac{b}{c}=\frac{9}{3}=3[/tex]
Deci b si c sunt direct proportionale cu 3 si 1
c) Stim ca: [tex]a=2b[/tex] si [tex]c=\frac{1}{3}b[/tex]
Atunci
[tex]2b+b+3\frac{1}{3}b=3b+b=4b=36\Rightarrow b=9[/tex]
Avem atunci
[tex]a=2b=2*9=18[/tex] si
[tex]c=\frac{1}{3}*9=3[/tex]
