If we are finding 10% the cost of the item you would set a proportion or an easier way would be .10x65 6.5 then you subtract that from 65 65-6.5 58.50 is the cost of the item 10% off but with shipping, it would be 58.50+7.25 65.75 is when there is 10% of the item but it is $65 only if the shipping is free and since 65<65.75 It is cheaper when the shipping is free