Răspuns:
{a;b;c;d} d.p. {2;3;4;7}=>[tex]\frac{a}{2}[/tex]=[tex]\frac{b}{3}[/tex]=[tex]\frac{c}{4}[/tex]=[tex]\frac{d}{7}[/tex]=k=>a=2k
b=3k
c=4k
d=7k
5 x a + b - c + 2 x d =115
5 x 2k + 3k - 4k + 2 x 7k =115
10k + 3k - 4k + 14k =115
9k + 14K =115
23k =115:23
k=5=>a=2x5=10
b=3x5=15
c=4x5=20
d=7x5=35
Explicație pas cu pas:
5x10+15-20+2x35=
=50+15-20+70=
=65-20+70=
=45+70=
=115
