can please tell me how to find gross profit. and how to slove 33 1/3%. please help

Tim Legler requires an estimate of the cost of goods lost by fire on March 9. Merchandise on hand on January 1 was $38,000. Purchases since January 1 were $72,000, freight-in $3,400, purchase returns and allowances, $2.400. Sales are made at 33% above cost and totaled $100,000 to March 9 Goods costing $10.900 were left undamaged by the fire; remaining goods were destroyed Your Answer Correct Answer Your answer is correct Compute the cost of goods destroyed. (Round gross profit percentage and final answer to 0 decimal places, eg. 15% or 125.)