Question

trei elevi au un numar de timbre. primii doi au 197, ultimii doi 188,iar primul si ultimul 171 timbre. Cate timbre are fiecare elev?

Answer 1

a+b+c=x
a+b=197 => a=197-b
b+c=188
a+c=171

Inlocuim pe ''a'' in ecuatia ''a+c=171''
Deci..
197-b+c=171
-b+c=171-197
-b+c=-26 
Inmultim cu ''-1''
b-c=26
Astfel avem
b+c=188 => b=188-c
b-c=26
188-c-c=26
188-2c=26
-2c=-162
2c=162
c=162:2
c=81 timbre
b=188-c
b=188-81
b=107 timbre
a=197-b
a=197-107
a=90 timbre
Presupun ca asa se rezolva..

Answer 2

a+b=197
b+c=188
a+c=171
a+b+b+c+a+c=197+188+171
2(a+b+c)=556
a+b+c=278

197+c+278
c=278-197
c=81
b+c=188
b=188-c
b=188-81
b=107
a+c=171
a=171-c
a=171-81
a=90

deci a=90,  c=81  si  b=107