Answer:
$520
Explanation:
1% of x is x times 0.01.
that means 10%of x is x times 0.1.
400 times 0.1 is 40.
40 is 10% of 400.
it was marked up by 30% so we need to times by 3.
40 times 3 is 120.
it was marked up so its addition.
400+120=520
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