Can you break down the solution for me for this math problem: Connor wanted to order some new books to read.  The website was offering free shipping over $50.00.  They also had a deal that when you buy 4 books; the first two were 25% off.  Book 1 cost 13.00 and Book 2 cost 15.00.  Book 3 & 4 were both $10.00 each.  How much more money did Connor need to spend to receive free shipping?