Ace of Diamonds purchased 70 diamond bracelets at $235 each and the regular selling price was $320. The store sold 50.00% of them at the regular selling price. During a sale, it sold another 30 of them at a markdown of 20.00%. The remaining units were sold at an additional markdown of 10.00%. Determine the net rate of markup based on total cost.

What is the net rate of mark up based on total cost? %