I am trying to figure out what my cash and sales discount amounts will be, but I seem to be doing something wrong. $3,547, terms 3/10, n/30.

Show your calcs and where / why you think you're missing the mark. Those terms simply mean that if you pay within 10 days the vendor will accept 97% of the total in full payment of the bill. If you choose to pay on or after 11 days, the full 100% is due no later than 30 days.