Find the selling price for each item given the cost and the percent of discount

Coat: 43$; 40% discount

100 - 40 =60 % which is 0.60

0.60 * full price = discounted price.
HOWEVER, your sentence is nonsense.
You sell ABOVE cost to make money
Are you sure you mean cost?
If so then we are talking "markup" not discount
and selling price = 1.40 * cost