Răspuns :
x-230-157=3156
x-387=3156
x=3156+387=3543
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4750+x-800=6700
x+3950=6700
x=6700-3950=2750
x-387=3156
x=3156+387=3543
-------------------------
4750+x-800=6700
x+3950=6700
x=6700-3950=2750
X-230=3156-157=x-230=2999
X=230+2999=x=3228
4750+x =6700+800=4750+x=7500
X=7500-4750=x=2750