Need help with #2 and #3 please...show formulas so I know where I went wrong please!

The postal service of St. Vincent, an island in the West Indies, obtains a significant portion of its revenues from sales of special souvenir sheets to stamp collectors. The souvenir sheets usually contain several high- value St. Vincent stamps depicting a common theme, such as the life of Princess Diana. The souvenir sheets are designed and printed for the postal service by Imperial Printing, a stamp agency service company in the United Kingdom. The souvenir sheets cost the postal service $1.80 each. St. Vincent has been selling these souvenir sheets for $8.00 each and ordinarily sells about 52,000 units. To test the market, the postal service recently priced a new souvenir sheet at $9.00 and sales dropped to 42,000 units. Required: 1a. Calculate the contribution margin for sale price of $8.00 each or $9.00 each? $8.00 Price $9.00 Price Unit sales 52,000 42,000 Sales $ 416,000 $ 378,000 Cost of goods sold 3,600 75,600 Contribution margin | $ 322,400 $ 302,400 1b. Does the postal service of St. Vincent make more money selling souvenir sheets for $8.00 each or $9.00 each? $8.00 $9.00 2. Estimate the price elasticity of demand for the souvenir sheets. (Negative amount should be indicated by a minus sign. Do not round intermediate calculations. Round your answer to 4 decimal places.) Price elasticity of demand (1.5385) 3. Estimate the profit-maximizing price for souvenir sheets. (Do not round intermediate calculations. Round your answer to 2 decimal places.) Profit-maximizing price