x : 5 =1400-900x-30=1000-200

Х:5=1400-900
х:5=500
х=500*5
х=2500
____________
2500:5=500
500=500

<span>x-30=1000-200
</span>х-30=800
х=800+30
х=830
____________
830-30=800
800=800