Answer:
$324.35
Step-by-step explanation:
Given a $249.50 cell phone with a 30% markup, to determine the selling price of the cell phone we need to first calculate 30% of $249.50 as seen below;

We'll now add $74.85 to $249.50 to finally get the selling price of the cell phone;

Therefore, the selling price of the cell phone is $324.35.