2)a+b=84
3intreg1/5=(3x5+1)/5=16/5
b=16/5·a=16a/5
a+16a/5=84
(5a+16a)/5=84
21a=84·5
a=420/21
a=20
b=16a/5=(16·20)/5=64
b=64
3)a+b+c=130
a a cheltuit: a-2a/3=x⇒(3a-2a)/3=x⇒ a=3x
b a cheltuit: b-3b/4=x⇒(4b-3b)/4=x⇒c=4x
c a cheltuit c-2c/5=x⇒(5c-2c)/5=x⇒3c=5x⇒c=5x/3
inlocuim in I relatie
3x+4x+5x/3=130
7x+5x/3=130
(3·7x+5x)/3=130
26x=130·3
x=390/26
x=15
a=3x=3·15=45
a=45
b=4x=4·15=60
b=60
c=5x/3=(5·15)/3=75/3
c=25