Nike uses the perpetual inventory system and sells $300,000 of sporting goods to Sears under credit terms

Question:

Nike uses the perpetual inventory system and sells $300,000 of sporting goods to Sears under credit terms of 1/10, net 30 on April 10, 2017. Nike's cost of the goods is $210,000, and it receives the appropriate amount of cash from Sears on April 20, 2017.
Journalize Nike's transactions on April 10, 2017, and April 20, 2017. How much gross margin did Nike earn on this sale?