690 - ( 720 - 420) - 120 = 270 ( это не равность)
1) 7** 6**<<span>9*9 *08
</span> ** ***<<span><span>97* 99*
</span>2)</span><span>998 999</span>>879 831
8ц1/17-(х+2ц3/17)=3ц9/17+15/17; (17*8+1)/17 -[х+(17*2+3)/17]=(17*3+9)/17+15/17; 137/17-[х+37/17]=60/17+15/17; 137/17-х-37/17=(60+15)/17; (137-37)/17 -х=75/17; 100/17-х=75/17; 100/17-75/17=х; (100-75)/17=х; 25/17=х; Х=1ц8/17;.ток 1 :3
1) = 8021188
2) = 7700451
3) = 7599370
4) = 3356566