Question

aflati nr x si y care verifica relatia x+y=10,x-y=2

Answer 1

$\left \{ {{x+y=10} \atop {x-y=2}} \right.$
__________________  scadem relatiile si  scapam de x
=> 2 y = 8
=>y=8/2 =>
 y=4
inlocuim intr-o reltie: x-4=2
=>x =2+4
=> x=6 

Answer 2

x+y=10
x-y=2
2
x |-----|--| )10
y |-----|

10-2=8
8:2=4(y)
4+2=6(x)