Can you explain to me how you find these along with the answers? This confuses me

CRAZY WAYNE'S FURNITURE OUTLET 55234 W.Jane St Sacramento, CA 94203 INVOICE NO. 3852 DATE: April 15, 20 Chuck's Furniture TO 425 Main St. ORDER NO.: SHIPPED BY: TERMS: 1292 USA LOGISTICS 2/10, n 30 Altus, OK 73521 QTY ITEM UNIT PRICETOTAL 10 Halogen Lamps 5 Ultrasuede Futon Cvr. 15 Chery Bookshelf 100.00 60.00 130.00 Tota a. Use the information on the invoice to calculate the extended amount for each item and the total invoice amount Invoice Total: $ b. Locate the terms of sale on the invoice and determine what you would pay on April 25th Amount Paid April 25th: $