x-y+z = 12
z+y = 6
z-x = 4
7+2x-y= ?

Aflati varog raspunsul)


Răspuns :

z-x=4 | *(-1)

x-z=-4
dar
x-y+z=12
adunand ultimele 2, obtinem
2x-y=8

atunci
7+(2x-y)=7+8=15
 us ugly as that!!




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