At $189, a firm can sell 16,930 stereo earphones (3.5 mm for android). These are premium earphones, guaranteed for 5 years. At this price, elasticity is estimated at 0.4. What is the change in total revenue (+ or -) if the firm drops price by 10%?

The correct answer is (-204,785)

Please show me how to this problem was solved thank you.

Module 3 Pricing Homework.