Answer:
$448.50
Step-by-step explanation:
"Marking up" an item by x% means to increase its price by x% of the original price.
Here, when marking up by 50%, you would multiply the original price by 1.5:
1.5*299 = $448.50
You wouldn't just multiply by .5 because that would only give you 50% of $299. You could multiply .5*299 and get $149.5, but then you'd have to add it to $299, which would get you $448.50 again!
The quicker way is to just multiply the original price by 1+x%.
Hope this helps!