Răspuns :
a+b+c=130
b=2a+5
c=a+b
deci
c=a+2a+5
c=3a+5
a+2a+5+3a+5=130
6a+10=130
6a=120
a=20
b=2*20+5=45
c=20+45=65
a+b+c=130
b=5+2a
c=a+b = a+5+2a=3a+5
rezultă a+b+c = a+5+2a+3a+5=6a+10
6a+10 = 130
6a=130-10
a=120:6
a=20
b=5+2a = 5+2x20 = 5+40
b=45
c=3a+5 = 3x20+5=60+5
c=65