30t+25t²/2=14
25t²+60t-28=0
D=3600+2800=6400
t1=(-60-80)/50=-2,8 не удов усл
t2=(-60+80)/50=0,4ч
15:30-14:30=1часа
150-100=100км
Vобщая=V1 + V2
V2= Vобщая-V1
V2=100-90=10км/час
<span>2/15y+3/4=5/6
</span>2/15y=5/6-3/4
2/15y=10/12-9/12
2/15y=1/12
y=1/12:2/15
у=1/12·15/2
y=5/8
<span>Ответ: у=5/8</span>
35 + 1072 +123 -1105,5 +3 = 127,5
2x/3x=2/3 (x)
15x/25y=3x/5y (5)
6a/24a=1<span>/4 (6a)
</span>7ab/21bc= a/3c (7b)
-2xy/5x²y= -2/5x (xy)
8x²y²/24xy=xy/3 (8x<span>y</span>)