So, firstly let us take a look at the formula below;
Markup%= selling price- cost/cost*100
We are going to proceed from the formula above.
●Selling price= $ 449.99
●Cost price= $ 275.59
Step 1
$ 449.99- $ 275.59= % 224.40
Step 2
$ 224.40/ $ 275.59*100= 81.4253057078
82% if was to be rounded.
ANS= 82%