<span>3,06:0,9x=17:10
</span>3,06 × 10 = 0,9х × 17
<span>30,6 = 15,3х
х = 2</span>
684 : 114 =6 часов
108*6=648км проехал 2
684+648= 1332
(56+14)-20=70-20=50
60-(20+13)=60-33=27
80+(12+5)=80+17=97
(30+70)-20=100-20=80
<span>9х + 1 = 10х - 1.
9х-10х=-1-1
-х=-2
х=2</span>
7, 16, 34, 70, 142
7+7=14+2=16
16+16=32+2=34
34+34=68+2=70
70+70=140+2=142