1) -0,8а + 1,2 = 64
-0,8а = 62,8
-а = 78,5
а = -78,5
2) 5/21у-2= -3*1/5
5/21у-2 + 3/5 = 0
( 5 +3(21у-2))/5(21у-2) = 0
(5+63у-6)/5(21у-2) =0
63у-1=0
63у=1
у=1/63
80=120
х=330
х=80*330/120
х=80*33/12
х=40*33/6
х=20*33/3
х=20*11
х=220
ответ:220см
<span>|х|-7 = 2
</span><span>|х| = 7+2
</span><span>|х| = 9
х = 9 и х = -9</span>