а)900-(14х+8):20=894
(14х+8):20=900-894
(14х+8):20=6
(14х+8)=6*20
14х+8=120
14х=120-8
14х=112
х=112:14
х=8
-----------------------------
900-(14*8+8):20=894
900-120:20=894
900-6=894
894=894
б) 500:(3у-7)+95=120
500:(3у-7)=120-95
500:(3у-7)=25
3у-7=500:25
3у-7=20
3у=20+7
3у=27
у=27:3
у=9
---------------------------
500:(3*9-7)+95=120
500:20+95=120
25+95=120
120=120