Sales proceeds and contribution calculation

Great Southern Co manufactures hairdryers for the hotel industry, which it sells for $12 each. Variable costs of production are currently $6 per unit. New production technology is now available which would cost $250,000, but which could be used to make the hairdryers for a variable cost of only $4.50 per unit. Fixed costs are expected to increase by $20,000 per year, 75% of which will be directly as a result of installing the new technology. Great Southern charges depreciation at 20% and seeks a return on its investments of at least 10%. The new technology would have an expected life of 5 years and a resale value after that time of $60,000. Sales of hairdryers are estimated to be 50,000 units per year. The management accountant has started preparing a spreadsheet to calculate the NPV of the project, Hello sir, in the above Question the sales contribution was asked to be calculated. The answer was given as $6- $4.5 = $1.5 $1.5* 50,000 units= $75000. I understand the variable cost after the project is being used. But I don't understand why a sales vale of $6 is used when the first line clearly says the selling price per unit is $12, and no more comments are made on this. Also for there was a blank space in the question to fill the sales proceeds for year 5. The answer to the sales proceeds was $60,000. Isn't that the amount received when reselling the investment. Aren't Sales proceeds just normal Sales value for a month which i think would be 50,000 units * $12 = $600,000. PLs requesting for help for explanation of the above 2 queries. thank you kindly, Sukaina.