Răspuns:
a = 21
b = 3
c = 7
Explicație pas cu pas:
[tex]\frac{a}{9} = \frac{c}{c-4} = \frac{28}{b} = \frac{7}{3}\\ \\ \frac{a}{9} = \frac{7}{3} \iff \frac{a}{3} = 7 \iff a = 21\\ \\ \frac{28}{b} = \frac{7}{3} \iff \frac{4}{b}= \frac{1}{3}\iff b = 3\cdot 4 = 12\\ \\ \frac{c}{c-4} = \frac{7}{3} \iff 3c = 7(c-4) \iff 3c = 7c - 28 \iff 4c = 28 \iff c = 7[/tex]
