Question

2 copii au 120 timbre.3/4 din nr. timbrelor primului reprezintă cat 1/2 din nr. timbrelor celui de-al doilea.Cate timbre are fiecare copil?

Answer 1

x+y=120
3/4x=1/2y
x=120-y
3/4*(120-y)=1/2y
360/4-3y/4=y/2
360/4=y/2+3y/4
360/4=2y/4+3y/4
360=5y
y=360/5=72
x=120-72=48 Deci un copil are 72 timbre si celalalt are 48 timbre.

Answer 2

a+b=120[timbre]
3/4 ·a=3a/4
1/2 ·b=b/2;
⇒3a/4=b/2
⇒3a·2=4b
⇒6a=4b
⇒3a=2b⇒a=2b/3;
⇒2b/3+b=120[timbre]
⇒2b/3+3b/3=120[timbre]
⇒5b/3=120
⇒5b=3·120
⇒5b=360
⇒b=72;[timbre-al doilea copil];
⇒a=2·72/3
⇒a=2·24
⇒a=48;[timbre-primul copil];