Question

Află a,b,c, dacă: a+b=c; a-b=b; b+c=20

Answer 1

a=10
b=5
c=15
a+b=c adica 10+5=15
a-b=b adica 10-5=5
b+c=20 adica 5+15+20

Answer 2

Se face sistem de ecutii la astea A+b=c A-b=b 2a=c+b Dar b+c=20 Deci 2a=20=>a20:2=>a=10 Acum a-b=b=>a=b+b =>a=2b Dar a=10=>10=2b=>b=10:2=>b=5 Acum a+b=c Dar a=10 si b=5 =>10+5=c C=15