(2/3)(1.2+1.7+2.1+2.9+3.3+3.8) =(2/3)*<span> (</span>(1.2+3.8) +(1.7+ +3.3 )+(2.1+2.9 ))=(2/3)(5 +5+5) = (2/3)*(3*5) =10.
5. а) -8 б) -20 в) -17 г) -133 20. 1) х=-35 2) у=-38 3) а=-7 4) b=2
4-2y=y-5
-y-2y=-4-5
-3y=-9
y=-9 : -3
y=3
Ураган пройдет 9 км, за 5 минут