I am trying to figure out the cost of merchandise destroyed on Feb. 7th given the following information:

Jan 1. Merchandise inventory $144,200
Jan. 1-Feb. 7 Purchases (net) 40,000
Jan. 1-Feb. 7 Sales (net) 70,000
Estimated gross profit rate: 40%
(gross profit rate=gross profit/net sales)

Can anyone help??