It's not clear what is the specific requirement of the question, but I'll assume a couple of situations to help you with your real problem.
Answer:
$45 (qualified)
$30 (did not qualify)
Explanation:
Percentage Calculations
Relative quantities are usually expressed as percentages (%). We say x percent of y is the proportion xy/100. When discounts or surcharges are applied, they are subtracted or added to the original quantity.
The question explains I receive a 10% discount off the original selling price if the total cost plus shipping is greater than $35. Let's assume the total cost plus shipping is $50. Since it's greater than $35, it qualifies for a discount. The discount is 10% of $50 = (10)(50)/100= $5. So the new total cost will be $50 - $5 = $45
Let's suppose now the total cost+shipping is $30. Since it's not greater than $35, no discount will be applied and we have to pay $30