Question

Află nr a , b , c ,știind că a+b=300 , b+c= 500, iar a+c=400

Answer 1

a+b     = 300 ,
     b+c= 500,
a      +c=400
se aduna toate
2a+2b+2c=300+400+500
2(a+b+c)=1200

a+b+c= 600  si
a+b     = 300
⇒ 300 + c = 600
c= 600 - 300 = 300
c= 300

a +c=400⇒a=400-c=400-300 =100
a=100
a+b=300
100 + b = 300 ⇒b = 300 -100 = 200
⇒b=200

deci a=100,  b=200 si c=300

Answer 2

a+b=300 →a=300-b
b+c=500→c=500-b
a+c=400inlocuind termenii a si c obtinem 300-b+500-b=400→2b=800-400= 400
b=400:2→b=200; a=100; c=300