{a;b;c}
{2;4;7}
[tex] \frac{a}{2} = \frac{b}{4} = \frac{c}{7} = k[/tex]
[tex] \frac{a}{2} = k[/tex]
a = 2k
[tex] \frac{b}{4} = k[/tex]
b = 4k
[tex] \frac{c}{7} = k[/tex]
c = 7k
6a + 3b - 2c = 180
6·2k + 3·4k - 2·7k = 180
12k + 12k - 14k = 180
24k - 14k = 180
10k = 180
k = 18
a = 2k = 2·18 = 36
b = 4k = 4·18 = 72
c = 7k = 7·18 = 126