Răspuns :
x+y=142;=>y=142-x
y+z=90=>z=90-y
x+z=156
x+90-y=156
x+90-142+x=156
2x-52=156
2x=208
x=104
y=142-104
y=38
z=90-38
z=52
y+z=90=>z=90-y
x+z=156
x+90-y=156
x+90-142+x=156
2x-52=156
2x=208
x=104
y=142-104
y=38
z=90-38
z=52
2X+2y+2x=142+90+156
=232+156
=338
X+y+z=338÷2
=169
Z=169-142=27
y=90-27=63
X=142-63=79
