Answer:
$450
Explanation:
after 15 weeks, stacy would have deposited a total of $25 × (15 - 1) = $350. (remember to subtract 1 from the 15 weeks since she did not deposit $25 during the week she opened the account, but only after that.)
now, we need to add this to the original deposit: $100 + $350 = $450.
therefore, after 15 weeks, there would be $450 in her account.
i hope this helps! :D