For this case we have the following definition:
[tex]d = v * t
[/tex]
Where,
d: distance
v: speed
t: time
Clearing the time we have:
[tex]t = d / v
[/tex]
The total driving time takes half an hour:
[tex]t = d / v1 + d / v2
1.5 = d / 30 + d / 20[/tex]
Clearing d we have:
[tex]1.5 * 30 * 20 = 20d + 30d
1.5 * 30 * 20 = 50d
d = (1.5 * 30 * 20) / (50)
d = 18 miles[/tex]
Answer:
she lives 18 miles far from the store
