[tex] \frac{a}{3} = \frac{b}{7} = \frac{c}{8} =k[/tex]
a/3=k => a=3k
b/7=k=>b=7k
c/8=k=>c=8k
2 * 3k + 5* 7k - 4* 8k=108
6k+35k-32k=108
9k=108
k=108:9
k=12
a= 3*k => a= 3*12 => a=36
b=7*k => b=7*12 => b=84
c=8 * k=> c=8*12 => c=96
~Verificare~
2 * 36 +5*84-4*96 =72+420-384=492-384=108 (A)
