Odpowiedzi

2010-03-30T17:02:47+02:00
V₁=s/10min - Paulina
v₂=s/15min - siostra

s=10v₁=15v₂
2v₂=v₁t
[2, bo 2 min]

v₁=1,5v₂
t=2v₂/v₁

t = 2v₂ / 1,5v₂
t = 2/1,5
t = 4/3 [min] = 1min 20s