<span>1,5(a</span>²<span>b)</span>³<span> (-6 2/3ab</span>⁴<span>)=-3/2*20/3*a</span>⁷<span>*b</span>⁷<span>=
- 40 a</span>⁷<span>b</span><span>⁷</span>
<span>3 1/7(-1.4a</span>³<span>b) (ab</span>³<span>)</span>²<span>=
22/7*14/10* a</span>⁵<span>*b</span>⁷<span>=4,4a</span>⁵<span>b</span><span>⁷</span>
V - скорость мальчика
Ve - эскалатора
V+Ve = 1/30
V-Ve = 1/150
Ve = 1/30 - V
V - 1/30 + V = 1/150
V = (1/150 + 1/30)/2 = 1/50
ответ 50