Answer:
14 full weeks.
Step-by-step explanation:
The phone costs $324 and she saved $56, so we subtract $56 from $324.
$324 - $56 = $268
She saves $20 each week so we divide $268 by $20 to get the number of weeks.
$268/20 = 13.4
It will take 13.4 weeks, but we have to round up because at 13 weeks she won't have enough saved. So 14 full weeks.
