Lakeside Marine received an invoice from Osborne Boats dated March 26 with terms 1 /15, n/45,

Lakeside Marine received an invoice from Osborne Boats dated March 26 with terms 1 ½ /15, n/45, ROG for four 19-foot Barracuda boats at $23,500 each, less 20%, 5%. The boats arrived on April 27. Lakeside made a payment of $60,000 on the account on May 10. How much does Lakeside still owe?